Sedlec developed around a Cistercian monastery founded in the twelfth century outside Kutná Hora. Tradition says an abbot returning from the Holy Land in the late thirteenth century scattered earth from Jerusalem in the cemetery, increasing its prestige as a burial place. The growth of the nearby silver-mining city brought wealth and population, while plague and the Hussite Wars added many deaths. As graves were reused, older bones were exhumed and stored in an ossuary, a common Christian practice that respected bodily remains while making limited cemetery ground available again.

A two-level Cemetery Church of All Saints was built in Gothic form around the turn of the fifteenth century, with a chapel above and charnel space below. War and destruction affected the monastery and church. During the early eighteenth-century renewal of Sedlec, Jan Blažej Santini-Aichel remodeled the cemetery church in his distinctive Baroque Gothic manner, strengthening and reshaping the building while retaining its funerary function. The present architecture therefore combines medieval origins and human remains with substantial early modern intervention rather than surviving unchanged from the first phase.

The Schwarzenberg family later owned the estate and commissioned woodcarver František Rint to arrange the accumulated bones in 1870. He disinfected and whitened remains and created the chandeliers, garlands, pyramids, chalices, monstrance forms, and Schwarzenberg coat of arms that define the interior. These are genuine nineteenth-century compositions made from human bones, not medieval decorations and not modern replicas. Estimates of the number of individuals vary widely, so precise popular claims should be treated cautiously. The display transformed an older charnel collection into a deliberately designed devotional and commemorative environment.

The ossuary endured political changes, state control, tourism, and heavy visitor pressure. Recent conservation has addressed structural movement, damp, ventilation, masonry, and the ethical treatment of remains. Specialists have dismantled, cleaned, documented, and reassembled some bone arrangements where necessary, so current appearance reflects careful conservation as well as Rint's design. Photography restrictions and behavior rules respond to the fact that the material is human and the building remains sacred. The site should not be described simply as macabre decoration detached from Christian beliefs about death, resurrection, prayer, and burial.

The Roman Catholic Parish of Kutná Hora–Sedlec owns and operates the Cemetery Church of All Saints with the Ossuary. It remains consecrated, and access is by timed ticket under capacity limits and parish regulations. The ossuary lies within the Kutná Hora World Heritage setting but has its own distinct history. Its surviving fabric includes the Gothic and Baroque Gothic chapel, historic graves, and Rint's bone assemblages, all maintained through modern interventions. Clear interpretation distinguishes medieval cemetery use, eighteenth-century architectural rebuilding, nineteenth-century artistic arrangement, and present conservation instead of assigning every visible feature to one legendary moment.