Mars has some amazing geological features. Many of the biggest and the best are on Mars.

Olympus Mons
The magnificent Olympus Mons, the largest volcano and the highest mountain in the solar system.

Olympus Mons from space.

Valles Marineris

Mars is home to the Valles Marineris, the largest, longest, and deepest canyon known in the solar system. It's so wide that if you were in the middle of it you wouldn't even see the sides. You can take a flight down the valley, in this Flight Into Mariner Valley video Marineris

The Northern Plains
Mars' northern hemisphere, appears to be a giant impact crater, 10,600 km long by 8,500 km wide, or roughly four times larger than the largest known impact crater, the South Pole-Aitken basin