A piece of Mars: Sandwiched between hills, a huge stepped amphitheater has been carved out of the rock by the wind. The scene is 770×577 m across, with each giant step about 20 m wide. Just imagine a huge concert taking place down in the bottom of this monstrous gap (except the acoustics on Mars aren’t so great). (HiRISE ESP_020534_1825, NASA/JPL/University of Arizona)