ROME -- 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...