In a city where traffic rumbles past the Colosseum and soccer fans celebrate victories among the remains of the Circus Maximus, it comes as no surprise that relics of the glory that was Rome turn up almost every day, and sometimes get in the way of the modern city's needs.

The perennial tug-of-war between preserving ancient treasures and developing much-needed infrastructure is moving underground, as the city mobilizes archaeologists to probe the bowels of the Eternal City in preparation for a new, 15-mile subway line.

Eyesore yellow panels have sprung up over the past months to cordon off 38 archaeological digs, often set up near famous monuments or on key thoroughfares of the already chronically gridlocked historical center.

Rome's 2.8 million inhabitants can rely on just two subway lines, the "Metro A" and "B," which only skirt the center and leave it clogged with traffic and tourists. Plans for a third line that would service the history-rich heart of Rome have been put off for decades amid funding shortages and fears the work would grind to a halt amid a trove of discoveries.

Those discoveries may now be just a shovelful away as archaeologists dig through more than 17 million cubic feet of earth, documenting finds that go from modern to Roman times. They will then sit down with planners of Rome's "Metro C" line to discuss the engineering nightmare of shifting stairwells and redesigning stations to preserve any relics of note.

"It's bit of a slalom to preserve the finds and still get the subway done," said Fedora Filippi, the archaeologist who oversees a dig in front of the baroque church of Sant'Andrea della Valle. "This is the daily life of urban archaeologists who must confront difficult and fascinating sites like this one."

In mid January, working amid the noisy traffic jam created by the dig, Filippi uncovered the massive cement foundations of a Roman public building dating back to imperial times.

Filippi said that further study is needed, but the 13-foot-thick wall could belong to a swimming pool or to a temple dedicated to the goddess Fortune, parts of a monumental complex built in the area by Agrippa, trusted general and son-in-law of Rome's first emperor, Augustus.

Other finds emerging across the city include Roman taverns found near the ancient Forum; cellars of 16th-century palaces located in the middle of Piazza Venezia and Roman tombs found outside the walls containing the remains of two children encased in amphorae.

Under Italy's strict conservation laws, it will be up to the state's archaeological office for Rome to decide whether a find will be removed, destroyed or encased within the subway's structures.

Angry rows between conservationists and urban planners frequently erupt when state archaeologists descend on building sites where finds have been made, snarling or canceling projects.

Countless public and private works have been scrapped over the years in Rome and across Italy, and it is not uncommon for developers to fail to report a find and plow through ancient treasures.

In 1999, the government defied preservationists by going through with a parking garage that sliced through a Roman villa during hurried preparations for the Holy Year celebrations. The decision caused outrage especially due to the previous discovery of mosaics and ceramics from the villa in a garbage dump on Rome's outskirts.

Archaeologists and planners have since learned to work together, said Francesco Rotundi, project manager for Metro C.

"There is an increased awareness on everyone's part," he told The Associated Press during a tour Thursday of the archaeological dig in the historical Piazza Venezia. "Solutions are found, even if they require more time and money."

Pointing to a hand-drawn sketch of the site, Rotundi said planners had already moved a circular underground corridor to avoid destroying the remains of a Renaissance palace located by the dig.

The archaeological probes are needed only to clear the way for stairwells and air ducts, as the line's stations and tunnels in the center will be dug at a depth of 80-100 feet _ below the level of any human habitation ever, Rotundi said.

The euro3-billion ($3.9-billion) project is due for completion in 2015, but parts of the 30-station line are scheduled to open in 2011, sporting high-tech automatic trains transporting 24,000 passengers an hour.

Locals and visitors say the new subway is painfully needed.

"There aren't sufficient lines to get to all the major attractions," said Steve Scanlan, a 48-year-old Londoner on vacation with his family. "You have to use taxis, buses, which are more troublesome."

But the delays may not be over yet. Archaeologists say no major finds have been unearthed so far, but most of the digs still have to reach the earth strata that date back to Roman times, where plenty of surprises may be lying in wait.