Run, do not walk to the ESA website and download the magnificent image of Hebes Chasma on Mars:
This is an extremely deep chasm (8000 meters deep -- that's nearly as deep as Mt. Everest is tall!) almost smack on the Martian equator, at the northern tip of the grand Valles Marineris, the canyon on Mars that's as wide as the Grand Canyon is long, and as long as the United States. This image from the high resolution camera on Europe's Mars Express has a resolution of 15 meters/pixel, so if any martians are playing tennis, you could just make out the court. They even have an anaglyph!
That image is stunning, fantastic. It may even edge out my other favorite Mars picture, and it's certainly a contender for my Top Ten pick of the year.