Today's Image of Mars comes from Mars Express and shows part of Syrtis Major, an area that once experienced intense volcanic activity. Syrtis Major is so large (1300 x 1500 km) that it can be spotted from Earth with even small telescopes.
By examining the number and size of craters in Syrtis Major, scientists have been able to determine that it is approximately 3 billion years old. New images of Syrtis Major show numerous lava flows that covered much of the original, ancient terrain, but the lava flows were forced around high, steep buttes, or isolated hills that could not be entirely engulfed by the lava flow.
Clicking on this image will take you to the original high resolution image from the ESA, but I highly recommend checking out their article on Syrtis Planum.