Albor Tholus is an extinct volcano in the Elysium Planitia area on Mars. It lies south of the neighbouring volcanoes Elysium Mons and Hecates Tholus. Albor Tholus is 2.8 mile (4.5 Km) high and has a diameter of 99 miles (160 Km) at its base. Its caldera has a diameter of 18.6 miles (30 Km) and is 1.9 miles (3 Km) deep. This is geologically interesting, since the depth of the caldera approaches the height of the volcano, which is unusual on Earth. Evaluations by Mars Express found that the volcanoes of the Elysium region were active over long periods. Albor Tholus viewed on Google Mars