Philolaus is a lunar impact crater that is located in the northern part of the Moon's near side.

This crater retains a well-defined form that has not changed significantly since it was originally created.

The inner wall of the crater has a complex system of terraces with a sharp-edged rim in locations where slumping has occurred.

On the exterior of the rim is an outer rampart that extends outwards for nearly half a crater diameter in all directions.

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Philolaus.