The interior of this formation is relatively flat and smooth, with no significant craterlets to mark the surface. The outer rim is battered, worn, and notched with past impacts. Only slight wrinkle ridges now mark where the western rim once lay.
The landing site of the Luna 21 space probe is located near the southern rim of Le Monnier. Lunokhod 2, a robotic roving vehicle deposited on the surface by Luna 21, covered a distance of 37 kilometers across the crater floor. It also surveyed the southern edge of the crater rim.
Le Monnier crater and its satellite craters taken from Earth in 2012 at the University of Hertfordshire's Bayfordbury Observatory with the telescopes Meade LX200 14" and Lumenera Skynyx 2-1
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Le Monnier.
Menzel, D. H.; Minnaert, M.; Levin, B.; Dollfus, A.; Bell, B. (1971). "Report on Lunar Nomenclature by the Working Group of Commission 17 of the IAU". Space Science Reviews. 12 (2): 136–186. Bibcode:1971SSRv...12..136M. doi:10.1007/BF00171763. S2CID 122125855.