Mars has the tallest known mountain on a planet of our Solar System, with a height of 22 km (14 mi).
Olympus Mons, volcano on the planet Mars, the highest point on the planet and the largest known volcano in the solar system. Centred at 19° N, 133° W, Olympus Mons consists of a central edifice 22 km (14 miles) high and 700 km (435 miles) across.