Apollodorus is an impact crater on Mercury located near the center of Pantheon Fossae, which is a system of radial grabens situated in the inner part of the Caloris basin. Its unusual appearance, with radiating dark troughs, led to a nickname of "the Spider" by scientists before its official name was decided.

In 2016, scientists released the first-ever global digital elevation model of Mercury, which combined more than 10,000 images acquired by NASA's MESSENGER. According to this model, the lowest point on Mercury resides in the Rachmaninoff basin and lies 3.34 miles (5.38 km) below the landscape average.

In June 1962, Soviet scientists at the Institute of Radio-engineering and Electronics of the USSR Academy of Sciences, led by Vladimir Kotelnikov, became the first to bounce a radar signal off Mercury and receive it back, initiating radar observations of the planet.