The Fatal Erfurt Toilet Collapse
In 1184, a gathering of German nobility turned into a tragedy when a floor collapsed, plunging dozens of elites into a massive cesspit. The victims drowned in liquid waste beneath the building.
King Henry VI had convened a royal assembly at the Church of St. Peter, but the wooden floor was simply not built to hold the weight of so many dignitaries. As the floor joists gave way, the guests plummeted into the latrine pit located directly underneath the floorboards. It remains one of the most bizarre and macabre mass casualty events in medieval history. The event is now famously remembered by historians as the Erfurt latrine disaster.
Source: Erfurt latrine disaster