Named after Eratosthenes - Greek astronomer, geographer (c. 276-196 B.C.).
Eratosthenes is a deep lunar impact crater that lies on the boundary. The crater has a well-defined circular rim, terraced inner wall, central mountain peaks, an irregular floor, and an outer rampart of ejecta. It lacks a ray system of its own, but is overlain by rays from the prominent crater Copernicus to the south-west. (wikipedia entry)