megandear:

Outside of Prague, in the Czech Republic, is a small Roman Catholic Church that looks normal on the outside but holds 40,000 to 70,000 skeletons on the inside. Officially called the Sedlec Ossuary, it is often just referred to as Bone Church. Around 1400, thousands of skeletons were dug up so that the church could be built in the middle of the cemetery. The lower chapel was to be an ossuary for the mass graves unearthed during construction. Around 1870, a wood carver was commissioned to make order from all the bones. The dead were arranged in macabre art to form four bell towers, a huge bone chandelier that contains at least one of every bone in the human body, garlands of skulls draping the vault, bones around the altar, a large Schwarzenberg coat-of-arms, the signature of the artist Rint, and many more bizarre artworks. The chapel, and underneath the church and cemetery, are all decorated with bones. People who died in war or a gruesome death which marred the bones were not used too much for decoration. Instead, those skeletal remains are locked away behind gates or form bone tunnels.