Helmut Siegert returned to the coast of Libya last year to follow up on a tantalizing discovery. In September 2000, his colleague Marliese Wendowski was excavating what she thought was a large farmhouse when, 12 feet deep in the sandy soil, she came across a floor covered with a stunning glass-and-stone mosaic of an exhausted gladiator staring at a slain opponent. The discovery had come too late in that year's expedition to pursue further, so the University of Hamburg archaeologists reburied the mosaic. "It was well preserved," Ziegert says. "I knew there had to be a lot more."

When Ziegert and his co-workers finally returned to the site—near the town of Homs, which is adjacent to the ancient Roman settlement of Leptis Magna—they found, mixed in with the ruins of a modest farmhouse, those of a stately villa that housed gladiators, ancient Rome's superstar athletes. The mosaics decorated the floor of an elaborate cold-water bathhouse and consisted of tiny pieces of green, brown and gold glass and stone laid in a thin layer of chalk atop about five inches of concrete. Ziegert, who has conducted digs all across northern Africa, was stunned by the works' size: five huge panels that stretched 30 feet. Luisa Musso, a specialist in mosaics and Roman archaeology at the University of Rome Three, says, "I've seen mosaics all over this area, and these are extraordinary."

The scenes captured the gore of the Roman amphitheater that stood nearby. In the panel Ziegert's team uncovered first, the slain gladiator's head tilts backward nearly out of the frame, in a technique more common to paintings than mosaics. In the other panels, four young men wrestle a wild bull to the ground with their bare hands, a warrior does lone battle against a long-antlered deer, and a gladiator wearing intricately patterned trousers hoists his shield over a stricken foe. Some antiquities specialists say the painterly touches indicate that a Roman artist probably created the mosaics. But other experts resent the implication that an African couldn't produce such sophisticated work. "It looks like the artist might have been trained at one of the local schools in North Africa," says Hafed Walda, a Libyan archaeologist based at the University of London's King's College.

The mosaic is a window onto a thriving Roman city at the height of the empire's hold on North Africa. Set in a natural harbor on Libya's North African coast, Leptis Magna was founded some 3,000 years ago by Phoenicians as a commercial trading post for the Mediterranean region. After centuries of political turmoil, the area joined the Roman Empire around 25 b.c. Walls and gates were built around the city later, but residents retained the right to own their land and control local affairs. Leptis Magna's traders did well under Roman rule, but after the empire collapsed, in the fifth century a.d., the city's prestige and population waned. The town disappeared completely in the 11th century. Today, the ancient settlement is nestled next to Homs, a bustling modern town that caters largely to archaeological missions and a growing number of foreign tourists.

Like many of Leptis Magna's original buildings, the villa that Ziegert has been uncovering was buried over time by the slow shifting of nearby hills. Musso guesses that the villa's owner was a prosperous local trader. Given the mosaic's artistry, she says, the trader would have had immense wealth. "Everyone who stepped into the villa would know immediately how rich he was."

Last June, Ziegert hired Libyan workers to lift the panels out of the ground, haul them more than a mile and cement them to the walls of the small Leptis Magna Mosaic Museum financed by Italian officials. The removal incensed some archaeologists, who claim that the mosaics were irreparably damaged. "The beautiful Roman artwork remained well preserved under the sand for almost 2,000 years, only to be hastily and clumsily unearthed," Giuma Anag, a technical adviser to Libya's Department of Archaeology, bemoans in an e-mail. "It will take a good restorer several years and a lot of money to rid the mosaic of its current steel-and-concrete base." Musso and others believe that instead of relocating antiquities, officials should arrange for security guards to watch over intact archaeological sites. "It's always better to leave something where it is," Musso says. "But one of the issues is that there is a great difficulty in finding money to preserve them on the spot."

Ziegert dismisses the concerns, saying that the mosaics were damaged centuries before during an earthquake around a.d. 200. Abdallah Elmahmudi, the scientific research director for Libya's Department of Archaeology, also denies the archaeologists harmed the artifact. "It was excavated according to scientific theories," he says. "The people are very good workers and used the materials that we have in the department."

The dispute highlights new pressures on Libya, which is promoting its archaeological ruins as a tourist attraction after decades as an international pariah. In February 2004, President Bush lifted the 23-year-old ban on U.S. citizens traveling to Libya; in September, air travel between the two nations resumed. The move came after Libya agreed to dismantle its nuclear weapons facilities and compensate the families of people killed in the 1988 bombing of a New York City-bound Pan Am airliner over Lockerbie, Scotland; 270 people, including 189 Americans, died in the terrorist act, committed by a Libyan intelligence officer now jailed in Scotland. The United States still limits exports to Libya, and the nation remains on the State Department's list of terror sponsors along with countries such as Iran, Syria and Cuba.

Still, hundreds of Americans have recently traveled to Libya on package tours to visit the ruins of Leptis Magna, Sabratha and Cyrene. Among the best-preserved ancient Roman and Greek towns on the Mediterranean, the sites nonetheless show signs of neglect. "They're fantastic, but they look like they have been put in the hands of caretakers who don't give a damn," says Wisconsin travel consultant Rex Fritschi. Standing in the lobby of a Tripoli hotel last October, he said his group had found garbage strewn at some sites and no working toilets at others. Government officials and archaeologists say they need more funds not only for excavating but also administering archaeological sites.

If the gladiator mosaics are any indication, Libya's potential as a window into the Roman Empire's past has only just begun to be tapped: less than a third of Leptis Magna, a 1,500-acre site, has been excavated. As archaeologists continue to work, visitors to the little museum can contemplate the Roman equivalent of an action movie. The mosaics, Musso says, "are so full of passion and drama, it's like watching a film. They are really cinematic."