Jamieson, Fausset and Brown on Judges 16:27

Jud 16:26-31. His Death.

27. there were upon the roof about three thousand men and women, that beheld while Samson made sport--This building seems to have been similar to the spacious and open amphitheaters well known among the Romans and still found in many countries of the East. They are built wholly of wood. The standing place for the spectators is a wooden floor resting upon two pillars and rising on an inclined plane, so as to enable all to have a view of the area in the center. In the middle there are two large beams, on which the whole weight of the structure lies, and these beams are supported by two pillars placed almost close to each other, so that when these are unsettled or displaced, the whole pile must tumble to the ground.