With a length of 600 kilometers and a depth of up to two kilometers, Mawrth Vallis is one of the biggest valleys on Mars and a possible landing site for the ESA ExoMars and NASA Mars 2020 missions. It is entrenched in the Arabia Terra highland, which is more than four billion years old, and ends in the great Chryse Planitia lowland region. This 9-image mosaic High Resolution Stereo Camera (HRSC) on board the European Mars Express spacecraft covers an area of ~330,000 square kilometers on the transition from the southern Martian highlands to the northern Martian lowlands. Mawrth Vallis is at the centre of the image. For the full-resolution version, see here.