Sure, they were just awnings, but they fact they worked in an awning for the entire Colosseum is impressive.
It was known as the valerium. It consisted of a canvas-covered, net-like structure made of ropes, with a hole in the center. This roof covered two-thirds of the arena, and sloped down towards the center to catch the wind and provide a breeze for the audience. Sailors, standing on special platforms, manipulated the ropes on command.
