Fact-checking Andrew McCarthy’s upcoming January/February feature, “The Three Faces of Rome,” got me thinking about the Eternal City ‘s 2,000-year past, layer upon dusty layer of it. Currently, only two metro lines serve the city of 2.5 million. A third , set to open in 2015, has unearthed archaeological artifacts (like the Dionysos head, unearthed near Via Sannio, Rome, above), many which will be exhibited in the stations themselves. What else has been unearthed by metros around the world? Here are some highlights I found in my research: In Athens, when the city expanded its metro to accommodate the 2004 Olympics, 30,000 artifacts were found scattered beneath 17 acres. During construction, a 11th or 13th-century shipwreck was discovered at Yenikapi, what had been a harbor in Byzantine Istanbul. Approximately 2,000 fossils (mastodon, camel, ground sloth) dating back 16.5 million years were located way beneath the surface of Los Angeles. Construction of Line 14 of the Paris metro unearthed canoe-shaped boats 32 feet below the banks of the Seine, dating to about 2,800-2,500 B.C., hinting at what may be the earliest human settlement in the area.