medieval:

Sedlec Ossuary

wiki: In 1278, Henry, the abbot of the Cistercian monastery in Sedlec, was sent to the Holy Land by King Otakar II of Bohemia. He returned with him a small amount of earth he had removed from Golgotha and sprinkled it over the abbey cemetery. The word of this pious act soon spread and the cemetery in Sedlec became a desirable burial site throughout Central Europe.

In the mid 14th century, during the Black Death, and after the Hussite Wars in the early 15th century, many thousands were buried in the abbey cemetery, so it had to be greatly enlarged.

Around 1400, a Gothic church was built in the center of the cemetery with a vaulted upper level and a lower chapel to be used as an ossuary for the mass graves unearthed during construction, or simply slated for demolition to make room for new burials.

After 1511, the task of exhuming skeletons and stacking their bones in the chapel was given to a half-blind monk of the order.