Tallest mountain in the Solar System

Tallest mountain in the Solar System
Who
Olympus Mons, Mars
What
25 kilometre(s)
Where
United Kingdom (Mars,)
When
01 January 0001

Olympus Mons is the highest mountain in the solar system. Its peak is 25 km (15 miles) above its base – nearly three times the height of Mt. Everest. Olympus Mons is designated a shield volcano because of its shape. Despite its great height, it has a very gentle slope. Olympus Mons is over 20 times wider than it is high.

It is the same kind of volcano as the active volcanoes currently "creating" the Hawaiian Islands. The line around Olympus Mons is a "basal cliff" that is as high as 6 km (3.72 miles) in some places.