Helmut Ziegert 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 expedition to pursue further, so the University of Hamburg archaeologists reburied the mosaic.

"It was well-preserved," Ziegert tells Smithsonian magazine. "I knew there had to be a lot more."

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 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, 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.

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," says Giuma Anag, a technical adviser to Libya's Department of Archaeology. "It will take a good restorer several years and a lot of money to rid the mosaic of its current steel-and-concrete base."

Luisa Musso, a specialist in mosaics and Roman archaeology at the University of Rome, 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."

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.

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."