The largest volcanic region ("center") on Mars, Tharsis Montes is approximately 2,400 miles across, 6 miles high and contains 12 large shield volcanoes. The summits of Tharsis Montes summits are about the same elevation as the summit of Olympus Mons, the largest of the Tharsis volcanoes. While not the largest of the Tharsis volcanoes, Arsia Mons has the largest caldera, or volcanic collapse crater, on Mars, having a diameter of 75 miles. The main difference between the volcanoes on Mars and Earth is their size and fresh appearance. Volcanoes in the Tharsis region are up to 100 times larger than those anywhere on Earth. This model is rendered with a 6x vertical exaggeration.