More than 2,000 years after Julius Caesar came here for provisions and decided to start a veterans colony, a new army has invaded -- a multinational force of archaeologists in what is perhaps the largest ongoing dig in the Mediterranean.

Led by Professor Richard Hodges of the University of East Anglia in England, 100 archaeologists from 19 nations, 60 Albanian undergraduates and dozens of local laborers are rotating in over the course of this summer's two-month digging season.

The scientific goal of this decade-long project is to learn how society was transformed at the end of the classical period of ancient Greece and Rome, but the city of Butrint is as much of an attraction. Over the course of 3,000 years, successive civilizations made this city their own. "It became a place in the middle of the Mediterranean where everybody came," Hodges said.

This year's dig is the third major excavation since the nonprofit Butrint Foundation began operations in 1994. Most of the team will work on the Vrina Plain, a flat marshland between steep mountain ridges on the coast of the Ionian Sea. It was the site of Caesar's colony, a Roman suburb just across a narrow channel from the 40-acre city.

The scope of Butrint's past excites archaeologists of many periods. It was "Troy in miniature" in Virgil's "The Aeneid"; legend says the city was founded by Trojan exiles, but that belief is not supported by archaeological evidence.

Butrint was first settled between 1000 and 800 B.C., Hodges said, most likely as an outpost to provide food for the large settlement on the island of Corfu. Its strategic location astride major trade routes made the city a player in the politics of the day. It was in turn Hellenistic, Roman and Byzantine. Then came the Venetians and Ottomans, who built forts to protect the city and nearby fisheries.

In Butrint's heyday in the 5th century, Hodges said, as many as 20,000 people lived there. Monuments from each period remain today, just yards apart.

The city faded into oblivion after the 14th century, becoming a silted-over hillside where shepherds grazed their sheep. It stayed that way until 1928, when a young archaeologist dispatched by the Italian Foreign Ministry arrived and dug wherever he could see ruins. Luigi Maria Ugolini excavated on a grand scale until his death eight years later, even installing a railroad to haul away all the dirt.

Ugolini excavated most of the city as it is seen today, including a Greek theater, a temple to the god Aesclepious, and a large 5th-century baptistry with a tile mosaic floor.

Besides the project on the Vrina Plain, the two other big digs of this decade were the excavation of a Roman villa and Byzantine church across Lake Butrint and a private home in the city called the Triconch Palace, a site Hodges calls "the best excavated sequence of a large Roman home in the Mediterranean."

The original aim of the Vrina dig was to investigate the Roman colony, and from its preliminary work the team has been able to reconstruct the way the Romans settled the plain. "The landscape is centuriated -- in other words, divided up and made into this planned colonial world," Hodges said. His team can discern street lines and building plots. Team members have identified a fallen aqueduct that brought water from a spring about four miles away.

Still, project director Oliver Gilkes said the most interesting discovery is from a later period. He and Hodges believe they have found the first ceramics dating from the Middle Ages ever recovered in the central Mediterranean.

These pottery shards were buried in a layer of thick, black soil typical of the medieval period. The archaeologists were slowly working through that layer as they excavated a site containing a large Roman dwelling and the apse of a 5th-century Christian church. Numerous 9th- to 11th-century Byzantine coins were found there as well.

Gilkes is intrigued by what appears to be evidence of a medieval structure built on top of the earlier ones. The church appears to have been continually occupied, modified and rebuilt. Stains in the soil indicate the postholes and beam slots of timber buildings, just the sort of subtle detail often lost in the past, when the medieval artifacts were just stuff in the way of archaeologists intent on finding older classical treasures.

"If you're digging up classical remains," Gilkes said, "you don't really have to be that careful. You just dig until you hit something hard -- a mosaic or floor or whatever. But if you do that, you don't realize the soil tells a story. The soil itself is something you can use."

Carefully sifting the soil by hand, archaeologists are now going down 31 inches over the entire area within the walls of the 5th-century church. In doing so, Gilkes said, they are looking at the beginnings of the Middle Ages, a period little understood in this part of the globe, when a new civilization arose out of the wreck of the ancient world. "What we have here is a most unique early medieval sequence, which I think is going to open the door on the medieval history of the Balkans and the Mediterranean in general," he said.

Nowadays, a project on the scale of the Butrint Foundation's is rare in the region. Hodges said many countries simply won't support big foreign missions. "For understandable reasons, there's a 'Gosh, we want to do our own archaeology,' and that's it," he said.

A number of factors made it possible for Hodges to undertake the project. As an impoverished Albania emerged from communist rule, the nation sought outside help in resuming the work that largely ceased when Ugolini died half a century before. The project benefited, too, from the financial backing of wealthy donors who started the Butrint Foundation to help preserve the landscape and the cultural heritage associated with it.

Hodges said the next step is to publish what they've learned. To dig too much could destroy the special nature of the place. The city and the national park that surround it have been designated as a UNESCO World Heritage Site.

Unlike many archaeological sites, the wide-open hinterland and unspoiled surroundings give it another dimension, said Ani Tare, director of Butrint National Park: "Butrint is a magical place, very beautiful. There is something very raw, I would say. It takes you back to time."

That timeless quality and a growing national pride of place are also putting Butrint on the tourism map. Preserving the past has become part of the debate over the future of this site. Tare is adamant that archaeology must take its place alongside preservation.

Hodges echoes that sentiment when he says the most gratifying part of the experience for him has been doing something that helps Albania.

"We're not just digging for loot," Hodges said. "We're digging with an idea of creating assets for the place -- intellectual, on library shelves, tourists, identity and so on."