Fidenae Amphitheatre Collapse 27 CE
In 27 CE, a wooden amphitheater in Fidenae, just north of Rome, collapsed during a gladiatorial show and became one of the worst sporting disasters in ancient history. The venue belonged to a promoter named Atilius, who cheaply built the structure without strong foundations and used substandard materials. On event day, as crowds filled the wooden stands, the pressure proved too much; the structure gave way under the weight.
Historians disagree on the exact toll, but Suetonius estimated about 20,000 deaths alone, while Tacitus put the combined number of dead and injured at up to 50,000.
After the disaster, the Roman Senate cracked down and banned people with less than 400,000 sesterces from hosting gladiator games; they required that future amphitheaters be built on solid foundations and that they pass inspections for structural soundness. Atilius himself was banished.