From the update:
Before I say anything else, here's an updated render for the Ruined Temple amphitheater tile --
Ah, dirt. Glorious dirt! This is the same dirt mapping texture we're using on all of the other tiles (where dirt is present, of course) so that it will be easy to mix-and-match. You will also find dirt on most of the Ruined Temple tiles to some degree, so that we can break up the stone pattern, and make it visually more appealing by itself, and when combined with other sets.
For those wanting to use multiple amphitheater tiles to make a small arena, you can also paint this dirt in a sand color... and you're good to go!