Mars has some of the most highly varied and interesting terrain of any of the terrestrial planets, some of it quite spectacular:
• Olympus Mons: the largest mountain in the Solar System rising 24 km (78,000 ft.) above the surrounding plain. Its base is more than 500 km in diameter and is rimmed by a cliff 6 km (20,000 ft) high.
• Tharsis: a huge bulge on the Martian surface that is about 4000 km across and 10 km high.
• Valles Marineris: a system of canyons 4000 km long and from 2 to 7 km deep;
• Hellas Planitia: an impact crater in the southern hemisphere over 6 km deep and 2000 km in diameter.
Much of the Martian surface is very old and cratered, but there are also much younger rift valleys, ridges, hills and plains.