Geography of Mars Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The shield volcano, Olympus Mons ("Mount Olympus"), rises 22 km above the surrounding volcanic plains, and is the highest known mountain on any planet in the solar system. It is in a vast upland region called Tharsis, which contains several large volcanos. See list of mountains on Mars. The Tharsis region of Mars also has the solar system's largest canyon system, Valles Marineris or the "Mariner Valley", which is 4,000 km long and 7 km deep. Mars is also scarred by countless impact craters. The largest of
Mons Massicus Mons Massicus Mons Massicus, a mountain ridge of ancient Italy, in the territory of the Aurunci, and on the border of Campania and Latium adjectum attributed by most authors to the latter. It projects south-west from the volcanic system of Rocca Monfina (see Suessa Aurunca) as far as the sea, and separates the lower course of the Liris from the plain of Campania. It consists of limestone, with a superstratum of pliocenic and volcanic masses, and was once an island; its highest point is 811 meters (2661 feet) above sea-level. It was very famous for its wine in ancient times.