Tharsis quadrangle Mount Everest and about as big in area as all of Europe. Tharsis contains a group of large volcanoes. Olympus Mons is the tallest. Tharsis is a land of great volcanoes. Olympus Mons is the tallest known volcano in the Solar System; it is 100 times larger than any volcano on Earth. Ascraeus Mons and Pavonis Mons are at least 200 miles across and are over six miles above the plateau that they sit on—and, the plateau is three to four miles above the zero altitude of Mars. Pavonis Mons, the middle in a line of three volcanoes, sits at
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.