Our planetary neighbor, Mars, has been a source of fascination for thousands of years. In recent times, it has even been discovered to still hold water very near the surface.
Upon initial inspection, Mars looks like arid, dusty, and desolate planet, but it does indeed have quite a few characteristics that make it stand out in the solar system; one being the trademark red hue of the Martian dust that you can see through a telescope or even in the night sky.
Another interesting feature on Mars is Olympus Mons, a volcano so big that you could fit the equivalent of just under 3 Mt. Everests underneath.
It takes the crown for the tallest volcano in the solar system, measuring in at a mammoth 21,229 meters (21.9 km/14 miles.) It would be labelled the largest mountain in the solar system if only it wasn't for a gigantic impact crater known as Rheasilvia central peak, which scars a rocky asteroid called Vesta that lies in the asteroid belt.
The last major eruption of Olympus Mons took place some 25 million years ago. It's difficult to imagine what would it be like if Olympus Mons was to once more erupt, but it'd surely be a cataclysmic event that'd drastically alter Mars.