With a diameter of 1146 km, Mare Imbrium is the largest mare associated with an impact basin, and is surrounded by three rings of mountains … the Montes Carpatus to the south, the Montes Apenninus to the southeast, and the Montes Caucasus to the east.
The impact that created Imbrium shattered the Moon's lithosphere, and left an original crater possibly 100km deep.
The image here shows the Apennines Mountains towering over the Imbrium plain … Casting deep shadows from their 5km peaks.
The Apollo 15 Landing Site lies in a small valley on the western side of the Apennines.
Commander David Scott and Lunar Module Pilot James Irwin spent three days on the Moon. The mission was the first not to land in a lunar mare, instead landing near Hadley Rille where the crew explored the area using the first Lunar Rover.