The rushed construction of a Roman stadium in 27 AD led to a catastrophic failure during its inaugural gladiatorial games, which likely killed more than 20,000 people and devastated the Roman Empire.
For source notes, images and to see a 3D rendering of what the Fidenae Amphitheater likely looked like, go to https://manmadecatastrophes.com/the-fidenae-amphitheater-collapse
To read the paper, "Failure at Fidenae: Visualization and Analysis of the Largest Structural Disaster in the Roman World," click here.