National Geographic : 2006 Jul
the past 2,000 years, the floor has washed out, forcing everyone to inch along an unseen preci pice in chest-high, scum-covered water. A joker in the group observes that it looks like schiuma, the cocoa-like foam on Italian espresso. At a pile of rubble-bones, pottery sherds, and caked mud that nearly fill the entire space of the cloaca-the adventure comes to a halt. The sewer's barrel vault clearly reaches into the darkness beyond-one wonders how far. Roma Sotterranea plans to send a remote controlled robot to probe beyond the barrier; Luca expects to confirm that the great drain reaches the Baths of Diocletian, nearly a mile northeast. Who knows what treasures lie along the way, he says, noting that archaeologists had recently pulled a colossal head of Emperor Constantine from a sewer just like this, prompt ing speculation that the first Christian emper or may have been the victim of damnatio memoriae, as the practice of obliterating the memory of despised emperors was known in ancient Rome. For Luca Antognoli, subterranean spaces like the Cloaca Maxima offer clues about how this city grew to rule an empire from the edge of Scotland to Baghdad, leaving its imprint indeli bly on Western history. COLLIDING WORLDS A modern billboard looms near an ancient sports stadium, built by A.D. 86 and paved over in the 15th century to create Piazza Navona. With a lost world of cultural treasures lying beneath city streets, construction workers and home remodelers stumble onto new finds almost daily. 1"