Tidbit - according to a local, the word "
arena" is derived from the word used to describe the
sand they placed on the floor of the colosseum (over the wood) to absorb the
blood and guts from the gory spectacles.
During the hotter days, a canvas-like covering was used to shade the spectators. This was ties to huge stone pegs outside the colosseum with ropes. Only a few of these remain today.
When you see pictures of the colosseum today, you'll see a lot of holes in the stone. When built, the ampitheatre was earthquake proof - the Romans used metal to hold the blocks of stone together. Over the years the practice of plundering places for building resources lead to the metal being removed and reused.
In fact a majority of the outer wall of the Colosseum did collapse in a subsequent earthquake.