What is the highest mountain on Mars?

The highest mountain on Mars is also the highest mountain and volcano in the entire solar system. It is called Olympus Mons and is 16 miles (24 kilometers) high which makes it about three times higher than Mt. Everest. In addition to being very tall, it is also very wide (340 miles or 550 kilometers) and covers an area larger than the entire chain of Hawaiian islands. Olympus Mons is a very flat mountain which slopes by only 2 to 5 degrees. It is a shield volcano built up by eruptions of lava.