ossuary

An ossuary is a chest, box, building, well, or site made to serve as the final resting place of human skeletal remains. They are frequently used where burial space is scarce. A body is first buried in a temporary grave, then after some years the skeletal remains are removed and placed in an ossuary. The greatly reduced space taken up by an ossuary means that it is possible to store the remains of many more people in a single tomb than if the original coffins were left as is.