In the year of the consulship of Marcus Licinius and Lucius Calpurnius, the losses of a great war were matched by an unexpected disaster, no sooner begun than ended. One Atilius, of the freedman class, having undertaken to build an amphitheatre at Fidena for the exhibition of a show of gladiators, failed to lay a solid foundation to frame the wooden superstructure with beams of sufficient strength; for he had neither an abundance of wealth, nor zeal for public popularity, but he had simply sought the work for sordid gain. Thither flocked all who loved such sights and who during the reign of Tiberius had been wholly debarred from such amusements; men and women of every age crowding to the place because it was near Rome. And so the calamity was all the more fatal. The building was densely crowded; then came a violent shock, as it fell inwards or spread outwards, precipitating and burying an immense multitude which was intently gazing on the show or standing round. Those who were crushed to death in the first moment of the accident had at least under such dreadful circumstances the advantage of escaping torture. More to be pitied were they who with limbs torn from them still retained life, while they recognised their wives and children by seeing them during the day and by hearing in the night their screams and groans. Soon all the neighbours in their excitement at the report were bewailing brothers, kinsmen or parents. Even those whose friends or relatives were away from home for quite a different reason, still trembled for them, and as it was not yet known who had been destroyed by the crash, suspense made the alarm more widespread.
As soon as they began to remove the debris, there was a rush to see the lifeless forms and much embracing and kissing. Often a dispute would arise, when some distorted face, bearing however a general resemblance of form and age, had baffled their efforts at recognition. Fifty thousand persons were maimed or destroyed in this disaster.
-- Tacitus, Annals, Book IV
This happened 20 centuries ago, under the reign of Tiberius.
On the 5th May 1992, part of the biggest football stadium in Corsica (in the village of Furiani) collapsed during a major match. 15 people died, 2000 were wounded. That's a lot less than the fifty thousand mentioned by Tacitus. However, it should be noted that the Furiani catastrophe and the much older one in Fidena share the exact same causes: greed from the entrepreneurs, combined with extreme affluence to a sportive event, and lousy security measures.