Grimaldi - 230 km wide
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Grimaldi was maker of moon maps in the mid 1600s. His maps were used by Riccioli, who named most of the moon's features. This is a pretty old crater - about 4 billion years. Millions of years after it was formed, Grimaldi was flooded with lava. For some reason there is a concentration of mass at Grimaldi that gives the crater some extra gravity pull. It can actually affect lunar-orbiting satellites by attracting them downwards.
Image: March 31, 2007