Brno Ossuary, Underground ossuary beneath St James Church in Brno, Czech Republic.

The Brno Ossuary is an underground ossuary beneath Jakubské náměstí and largely under the Church of St. James. It holds the remains of over 50,000 people, making it the second-largest ossuary in Europe after the Catacombs of Paris. It was rediscovered in 2001 and opened to the public in June 2012.

The site served from the 13th century until 1784 as a repository for bones from the cemetery adjacent to the church, with many remains originating from plague victims during 17th and 18th century epidemics and war dead.

The arrangement of remains provides insights into social structures, as people from all walks of life were interred together, from nobility to the impoverished, their skeletal remains transferred here after the original cemetery was dissolved.

Access to the chambers is located at Jakubské náměstí, reachable by tram lines 4 and 9, with guided tours lasting approximately 30 minutes and a moderate interior temperature maintained throughout the year.

Scientific analysis of the bones revealed that complete darkness preserved natural pigmentation patterns, with yellow discoloration indicating cholera deaths and reddish hues marking plague cases, enabling modern epidemiological research into historical disease outbreaks.