Modern-day Mexico City is built on top of centuries of previous settlements, so it's not unusual for ancient tombs to occasionally be uncovered beneath the city's streets. It is, however, strange to find 10 ancient skeletons arranged in a spiral with their bodies interlocked, as archaeologists recently did. The 2,400-year-old burial was discovered during salvage excavations of an ancient village beneath the campus of the Pontifical University of Mexico, in southern Mexico City, the National Institute of Anthropology and History (INAH) announced.