Mars has the largest volcano in our solar system. Its name is Olympus Mons. It is 24 km high and 550 km across. It is 3 times taller than Mount Everest. Mars also has a solid crust like Venus which doesn't move like earth.

Layers of Mars

Layers of Mars

Formation of volcanoes

Formation of volcanoes

Melted rock pushes upward in the same weak spot in the crust for 100 of years forming the largest volcano in solar system.