Catacombs in Paris...Quite Bizarre

"These underground tunnels contain the anonymous bones of six million permanent Parisians. In 1785, the Revolutionary government of Paris decided to make its congested city more spacious and sanitary by emptying the city cemeteries (which traditionally surrounded churches) into an official ossuary. The perfect locale was the many kilometers of underground tunnels from limestone quarries, which were, at that time, just outside the city. For decades, priests led ceremonial processions of black-veiled, bone-laden carts into the quarries, where the bones were stacked into piles 5 feet high and as much as 80 feet deep behind neat walls of skull-studded tibia. Each transfer was completed with the placement of a plaque indicating the church and district where that stack of bones originated and the date they arrived."

A good photo link can be found here.