"You want to see what is happening to the Casbah?" the slender man asks in French, as I make my way down a steep stone staircase that leads to the Mediterranean Sea. Before venturing into this storied hillside quarter of Algiers, a labyrinth of shadowy alleys and cul-de-sacs filled with idle youths casting suspicious gazes upon outsiders, I'd been warned to keep my guard up, but this fellow's earnest manner persuades me he can be trusted. Introducing himself as Oualid Mohammed, he leads me down the Rue Mustapha Latreche, named after an Algerian guerrilla who fell fighting the French in the Casbah during the war of independence that lasted from 1954 to 1962 and concluded when France ended colonial rule. Then he stops before a crumbling two-story house. "That's where I live," he says. The entire front section is a ruin; the second floor has collapsed onto the first, and the hallway is filled with rubble.

On May 21, 2003, Mohammed tells me, an earthquake measuring 6.8 on the Richter scale struck about 40 miles east of Algiers, killing hundreds of people in this part of North Africa and badly damaging the Casbah. A few weeks later, a government team designated the family's house, which had developed dangerous cracks in the walls and ceilings, a priority for renovation. Then, Mohammed says, in their rush to begin, workmen removed several wooden beams, and the house caved in. Today a dozen family members live jammed into the two remaining rear rooms, waiting for a promised reconstruction to begin. "Nobody from the government has talked to us in two years," he tells me.

Mohammed leads me past the debris-strewn remnants of the house's front, through the kitchen to a dim room in the back. An elderly woman in a hijab, his mother, sits on a tattered couch, eating from a plate of olives and bread. A young man is scrunched up on a windowsill, asleep. Mohammed's father, a slight 71-year-old, shuffles into the room. He is Oualid Meziane, who turns out to be a Casbah hero. As a teenage resistance fighter, Meziane says, he carried five-gallon jugs of bomb-making chemicals from safe house to safe house, sometimes under the noses of French paratroopers, and distributed copies of the banned, pro-independence newspaper, El-Moudjahid. "We all lived in fear for our lives," he says. "There would be a knock on somebody's door at midnight, and a friend would be taken off—and guillotined." These days Meziane gets by on a $70 monthly pension and a small disability payment for the gunshot wound he got in the crossfire of a battle between Islamic fundamentalist guerrillas and the Algerian Army in 1995. "The real fighters in the war of independence didn't get their due," Meziane says, glancing at his disintegrating abode. "Look at how we're living now."

Spilling down precipitous hills overlooking the Mediterranean Sea, this mazelike quarter of Algiers, the capital of Algeria, has long conjured up both Arab exoticism and political turbulence. Dating back to Phoenician times but rebuilt by the Ottomans in the late 1700s, the Casbah has served over the centuries as a refuge for pirates, freedom fighters, Islamic militants and petty thieves, all of whom found easy anonymity in its alleys and houses sequestered behind imposing stone walls.

But the often violent history of the Casbah has obscured an appreciation of the quarter's architectural and cultural riches. Preservationists consider it one of the most beautiful examples of late Ottoman style. Its once-whitewashed structures, facing onto narrow passages and constructed around enclosed courtyards, contain a wealth of hidden treasures—marble floors, fountains, carved lintels, intricate mosaics. For generations, writers and artists have celebrated the mystery, tragedy and rhythms of life in the Casbah in literature and painting. "Oh my Casbah," wrote Himoud Brahimi, the poet laureate of the quarter, in 1966, four years after the Algerian resistance defeated the French occupiers. "Cradle of my birth, where I came to know loyalty and love. How can I forget the battles in your alleys, that still bear the burdens of war?" Djamila Issiakhem, who grew up here in the 1960s as the niece of a famous Algerian artist, remembers the vibrant Casbah of her youth as a place where women and girls, escaping their traditional confinement, congregated in hammams, public baths, to gossip and discuss marital prospects. (The suggestive entreaty, "Come with me to the Casbah," is not from the 1938 movie Algiers, starring Charles Boyer, but from an impersonation of Boyer by the cartoon character Pepé Le Pew, in The Cat's Bah, an animated short.)

But the Casbah's glory days ended decades ago, and much of the old city has crumbled into ruin. During the war for independence, thousands of rural Algerians flocked to the Casbah, where life was marginally safer and rents were cheap. The population climbed from 30,000 in 1958 to more than 80,000 today; as many as ten families crammed into some dwellings, putting unbearable strains on many houses. Earthquakes, torrential rains and flooding eroded foundations and walls further, and when one house fell, it often took down two or three others with it. Today much of the Casbah is a dingy slum, its refuse-strewn lots and fissure-ridden houses reeking of sewage and uncollected garbage. Of 1,200 traditional Ottoman-era buildings, just 680 are considered in good condition. Within a generation, some preservationists say, it is possible that the entire quarter could be uninhabitable. "The Casbah has lost its soul," says Issiakhem, who leads tours of it for Western diplomats and a handful of foreign tourists. "The question is whether we can ever get it back."

It may be too late. Valuable time was lost during the past two decades, when the country was engulfed in a brutal civil war, known here as the periode noire, or "black time." The war broke out in January 1991, after the country's military regime canceled elections that almost certainly would have brought an Islamist party to power. For nine years, Islamic terrorists and Algerian security forces battled in cities and the countryside, and perhaps 150,000 people, most of them civilians, died in terrorist bombings, reprisals and other attacks. "The Casbah was a no-go territory," I was told by Belkacem Babaci, a historian and radio-show host who was born in the quarter in 1941. "Even for somebody like me, who lived there most of his life, it was unsafe." The war wound down in 2000, under President Abdelaziz Bouteflika, a former liberation fighter who continued to send the army to pursue Islamic guerrillas while offering amnesty to those who gave up their weapons. (Perhaps 1,000 armed Islamic radicals, some of whom recently declared allegiance to Osama bin Laden, still carry out attacks against police posts and isolated farms from sanctuaries in Algeria's deserts and mountains. Recently, Al Qaeda claimed responsibility for an April 11 bombing in central Algiers.) When Babaci returned to the old quarter in 1998, after nearly a decade, he was shocked to see how it had degraded.

The coming of peace to Algeria hasn't made the government any more enthusiastic about preserving the old city. Unlike the ancient quarter of Bukhara in Uzbekistan, for example, which has benefited from state support, the Casbah has seen almost no public funding. It isn't for lack of resources: the Algerian government earns $4 billion a month in oil and natural gas revenues, and is believed to have $80 billion in cash reserves. Tourism, in a country still focused on maintaining stability, does not rank high as a government priority—Algiers has only a handful of decent hotels, and the country's hundreds of miles of beaches remain virtually undeveloped. Then there is the Casbah's long-standing reputation as a breeding ground for rebellion. "For the government, the Casbah is a treacherous place," says Abdelkader Ammour, secretary-general of the Casbah Foundation, a preservation group that got the Casbah named a Unesco World Heritage site in 1991. Since then, the foundation has painstakingly mapped the area, house by house, assessing the condition of each structure and outlining restoration strategies. But it has struggled for more than a decade to raise funds and awareness.

Before arriving in Algiers, I had been warned that even venturing into the old quarter would not be smart. Colleagues who had covered the civil war in the 1990s described the place then as a haunt for Islamic militants with a violently anti-Western agenda. Even U.S. diplomats who want to visit the Casbah must first get permission from the government, which provides them with armed security guards. But my local contacts assured me the reports of danger were exaggerated, so, with my guide and driver, Mohammed Ali Chitour, an unemployed civil servant, I head there on a bright morning without escorts. As a gentle salt breeze wafts from the harbor, Chitour leads the way down an ancient stone staircase, hemmed in by teetering mud- and concrete-brick buildings with stucco facades long since disintegrated.

We enter a gloomy world of shadows and dust, of braying donkeys and veiled women, of shafts of sunlight filtering through narrow corridors, and the smells of the sea, fresh baguettes and rotting fruit. The staircase turns into an alley, or ruelle, about 12 feet wide. We walk past elaborately carved Ottoman portals that shine through the gloom; one has a black iron door knocker in the shape of a fist, another is flanked by a pair of spiraling, slender columns. The cantilevered overhangs of several houses, supported by pole-like wooden beams, extend so far into the passage they almost touch. We pass beneath an archway formed by a second-floor chamber that vaults between two houses. (An aperture in the vault, dating to the Ottoman era but still of use today, allows the Casbah's female denizens to see out, without being spotted themselves.) Tiny passages, known as impasses, spill off the longer alley, ending abruptly in a wall of crumbled brick or masonry. On the lintel of one three-story house, I spy an old Star of David engraved in the stone, evidence of a Jewish presence once upon a time. Just beyond the house, Abdullah Shanfa, a near-toothless man of 54, welcomes Ali and me to his home. We enter a spartan central courtyard, ringed by a three-story loggia, or wraparound arched gallery—a classic Ottoman-era structure built about 300 years ago. The sun has given way to a drizzle; rain trickles through the open skylight onto a slightly sloped floor and drains into gullies.

Shanfa climbs onto his rooftop terrace and clambers to the adjoining roof—six feet higher than his own. "Come on," he says, extending a hand. Trying not to notice the 40-foot drop to the refuse-strewn alley, I grab the edge of the rooftop and hoist my body over the side. I stand up and take in the scene. Like a beehive, the Casbah clings to the hills around me, its dense sea of houses broken by domed mosques and minarets; I can hear the hubbub of crowds in an unseen souk, an Arab market, and the shouts of children playing soccer in an alley below. Beyond the quarter, a sweep of undistinguished, French-colonial buildings rises along the seafront. The Mediterranean, steely gray in the drizzle, laps at the shore. "Better enjoy the view while you can," he tells me. "Bit by bit the Casbah is being destroyed."

A minute later we're joined on the roof by a gaunt, bearded man, Nourredine Bourahala, 56. Like almost everyone else of a certain age in the Casbah, he claims to have been a member of the anti-French resistance. "The French troops picked me up when I was 7 and beat me with batons," he tells us. "I didn't speak the language then, so I don't know why they beat me, but I became a freedom fighter then and there." He leads us back into the alley, past Corinthian columns standing alone like sentries, rubble-strewn lots, houses with facades peeled away, and shells of dwellings that look more Baghdad than Algiers. As we walk, he shows us an old black-and-white snapshot of three Kalashnikov-carrying young men. "Do you recognize the one in the middle?" he asks. The pugnacious visage, he says, belongs to "Ali LaPointe," the small-time crook turned leader of a cell in the anti-French insurgency, whose short life was immortalized in the 1966 film The Battle of Algiers, which unfolds mostly in the Casbah. After a ten-minute walk, we arrive at the house—now rebuilt—where Ali LaPointe and three other young fighters were blown up by French counterinsurgency forces in October 1957, the incident that provided the dramatic opening and finale of the film. The house has been turned into a shrine, attended by an honor guard and adorned with Algerian flags and photocopies of newspaper articles chronicling the bloody struggle. Over the next three days, I'll confront the ghost of Ali LaPointe (real name: Ali Amar) at every turn. Little boys approach me in the alleys, reverently murmuring his name. And everywhere, grizzled veterans like Bourahala—who says he saw Ali LaPointe many times but spoke with him only once—recall their encounters with him as the high point of their lives.

The Casbah has been demolished—and resurrected—many times over two millennia. Around the sixth century b.c., the Phoenicians built a trading port, Ikosim, on the flat ground along the sea. The Romans occupied the same site shortly before the birth of Christ; it was sacked and burned by the Vandals in the fifth century. A Berber Muslim dynasty founded a new city on the ruins, calling it El Djazair, or the islands, named after a latticework of islets just off the coast that form a natural breakwater for the harbor. During the next 500 years, various Berber dynasties surrounded the city with walls and extended it up into the hills.

After Algiers came under Ottoman rule in 1516, they turned the old, walled city into one of the triumphs of North African architecture: city planners built 100 fountains, 50 hammams, 13 large mosques and more than 100 prayer halls. (The word "casbah," from the Arabic for fortified place, came to be used not only for the citadel at the summit of the hill, but for the entire city below.) The walled city, under constant threat from European invaders, enforced a curfew, but it was invoked with style: at night a flutist made the rounds, playing a Turkish melody called a coupe jambe, to announce it. And the Casbah was awash in wealth: Algerian privateers plied the Mediterranean, plundering European ships and often holding captives for ransom. Fra Filippo Lippi, the master painter of the Italian Renaissance, was taken as a prisoner to the Casbah; so was Miguel de Cervantes, author of Don Quixote, following a sea battle in 1575, and ransomed back to Spain after five years—and four escape attempts—for a few hundred gold ducats.

To local historians, including Belkacem Babaci, this Ottoman period represents the apex of the nation's power and glory. Babaci argues that the corsairs had every justification for their actions, considering the declaration of war against the Ottomans by, at various times, Spanish and French rulers. "The Europeans launched 17 expeditions against Algeria in 1541 alone," he told me, as we sipped coffee on the terrace of the El Djazair Hotel, a colonial-era villa perched high on a hill overlooking the Casbah. "Thirty thousand soldiers were sent to attack the Casbah, in revenge for the ‘insolence' of the Algerian corsairs, but they failed."

What the Europeans couldn't destroy, natural disaster did. In 1716, an earthquake flattened three-quarters of the Casbah; the Ottomans rebuilt the city over the next quarter century. By 1871 the French had defeated the Ottomans and indigenous Algerians. They would subject the country to 132 years of French colonial rule. Believing that the Casbah's hivelike alleys offered ideal conditions for armed resistance, the French razed houses within its northern perimeter. They also bisected the city with a central boulevard, the better to move troops, and widened other streets. These thoroughfares, bordered by now-crumbling apartments with French windows and filigreed balconies, provide a dissonant taste of Paris in a deeply Arab milieu. The French face-lift, however, failed to tamp down the spirit of resistance.

Mohammed Ali Chitour and I are walking through a neighborhood near the top of the Casbah. Unlike the mottled brown facades and garbage-strewn alleys of the rest of the old city, the buildings here are whitewashed and sparkling, even the cobblestones polished and clean. In 2000, the Casbah Foundation, in cooperation with the then-governor of Algiers, Cherif Rahmani, an ardent preservationist, undertook the most ambitious project yet to save the old city. Reasoning that rehabilitating the quarter would be feasible only if the homes were first emptied, Rahmani spent about $5 million to buy out landlords and relocate 498 families from Sidi Ramdane to apartments in modern Algiers. According to Babaci, who helped to coordinate the program, the idea was to "open the empty houses, let in the sea air and sun, make them breathe again. It would be like operating on the sick, letting them stabilize, letting them convalesce."

The city got as far as repainting the facades before renovation ground to a halt. Rahmani grew disenchanted and left; his successor turned cold on the project. "I was terribly disappointed," Babaci told me. "At the moment we were just getting off the ground, the whole thing stopped." Today many of the buildings remain padlocked, and "the insides are rotting," I was told by Mohammed Skakre, 78, a local resident, as he sat on a rickety chair in a cobblestone alley in the heart of the whitewashed area. "All the renovation is just talk," he continued. "It's been going on like this for 100 years." The Casbah Foundation isn't the only institution that has been frustrated by the Algerian government: two years ago, a U.S. government-funded development program offered substantial grants for the quarter's rehabilitation if Algeria would make matching contributions. Enthusiastic municipal officials completed the paperwork, but somehow the wali, or governor, of Algiers never finalized the contracts. "This guy stopped a project that could have done a lot of good, and he waited until the eleventh hour to pull the plug on it," says one Western diplomat in Algiers. Last year, impatient Unesco officials threatened to strip the Casbah of its World Heritage status, which would make raising awareness and funding even more difficult. "If I weren't an optimist, I would have closed the door a long time ago and turned my back on the place," Babaci told me. "I still believe it's possible to save it, but you need to empty it, and you need to find qualified people who will respect the style, the materials. It's a huge challenge."

For the moment, a few well-heeled individuals are taking the lead in rescuing the Casbah on a house-by-house basis. On one of the final days of my stay, a guide from the Casbah Foundation led Ali and me down an alley near a busy market. We'd come to meet Moulidj Zubir, whose 400-year-old, once-derelict villa, owned two centuries ago by the British ambassador, serves as a model, we'd been told, of what the old quarter could look like. Zubir, a white-bearded man in his 70s, met us at the entrance. "This was a maison de maître," a master's house, he explained, leading us through a marble-tiled entrance hall to a three-story loggia. Sunlight filtered through a crystal skylight, softly illuminating a lavishly renovated palace. Two stories of colonnaded arches, hung with dozens of brass and copper lanterns, encircled the gallery. Each floor was a feast of balustraded balconies; dark teak screens; arches embellished with mosaics of orange, peacock-blue and sea-green flora; thick oak doors inlaid with brass flowers.

Salons and bedrooms off the loggia contained silver samovars, Syrian marble-inlaid chairs, Persian carpets, silk curtains. Leading us to the top floor, Zubir gazed down into the atrium. "There are maybe four or five other people who have done what I've done, but no more than that," he said. "I did it for my son, so that he can continue living in the Casbah after I'm gone."

As Ali and I stepped back into the dank alley, a man wearing a dirty T-shirt and shorts emerged from a house across the road and invited us inside. The place looked like a "before" photograph of Zubir's: broken marble floor tiles, fissure-laced walls, rain puddling in the courtyard. Our host smiled apologetically. "We'd love to fix it up," he said. "But that costs money, and we don't have a sou." For the handful of preservationists trying desperately to save Algeria's irreplaceable treasure, it was an all-too-familiar lament.

Writer Joshua Hammer recently moved to Berlin. Photographer Eric Sander is based in Paris.