Melas, Candor, and Ophir — Valleys of Mariner
Valles Marineris — first captured by Mariner 9 spacecraft, is the Grand Canyon of the Red planet, which is defined as an intricate system of large depressions or chasms, stretching some 4,000 kilometers along the Martian equator.
If you were standing at the base of it, to the north (over the canyon’s central region), you would see Melas Chasm. Behind it, are the Candor Chasma and Ophir Chasm, lying near the horizon.
Overall; Melas, Candor and Ophir are about 200 kilometers wide and 5 to 7 kilometers deep.
Image credit: G. Neukum (FU Berlin) et al., Mars Express, DLR, ESA