Plato is a lava-filled lunarimpact crater on the Moon. Its diameter is 101 km. It was named after ancient Greek philosopher Plato. It is located on the northeastern shore of the Mare Imbrium, at the western extremity of the Montes Alpes mountain range. In the mare to the south are several rises collectively named the Montes Teneriffe. To the north lies the wide stretch of the Mare Frigoris. East of the crater, among the Montes Alpes, are several rilles collectively named the Rimae Plato.
The age of Plato is about 3.84 billion years, only slightly younger than the Mare Imbrium to the south. The rim is irregular with 2-km-tall jagged peaks that project prominent shadows across the crater floor when the Sun is at a low angle. Sections of the inner wall display signs of past slumping, most notably a large triangular slide along the western side. The rim of Plato is circular, but from the Earth it appears oval due to foreshortening.
The flat floor of Plato has a relatively low albedo, making it appear dark in comparison to the surrounding rugged terrain. The floor is free of significant impact craters and lacks a central peak. However, there are a few small craterlets scattered across the floor.

Vallis Alpes (Latin for "Alpine Valley") is a lunar valley feature that bisects the Montes Alpes range. It extends 166 km from the Mare Imbrium basin, trending east-northeast to the edge of the Mare Frigoris. The valley is narrow at both ends and widens to a maximum width of about 10 km along the middle stretch. 
The valley floor is a flat, lava-flooded surface that is bisected by a slender, broken, cleft-like rille. The center rille is a challenging target for telescope observation from the Earth and described as, "notoriously hard to spot."=10.5px The rille itself is longer than the valley proper, at 196.65 km ± 10.98 km, and has a width of 0.58 km ± 0.09 km and depth of 77.69 m ± 28.07 m.
Most likely this valley is a graben that was subsequently flooded with magma from Mare Imbrium and Mare Frigoris.=10.5px However, the valley could have been formed by stress fractures due to expansion of the mantle or contraction after solidification of regolith. It is not dissimilar to other linear features radiating from Mare Imbrium, and the impact event which created the Imbrium basin may have also led to the stresses creating Vallis Alpes. Lava flooding and thermal or tensional stress fractures are two causes of graben formation. This valley was discovered in 1727 by Francesco Bianchini.

Source: Wikipedia