Rheasilvia

Rheasilvia /ˌriːəˈsɪlviə/ is the most prominent surface feature on asteroid 4 Vesta and is believed to be an impact crater. 505 kilometres (314 mi) in diameter, it is 90% the diameter of the asteroid, making it one of the largest craters in the Solar System, and at 75°S latitude, covers most of the southern hemisphere. It partially obscures an earlier crater, named Veneneia, that at 395 kilometres (245 mi) is almost as large. It was discovered in Hubble images in 1997, but was not named until the arrival of the Dawn spacecraft in 2011. It is named after Rhea Silvia, a mythological vestal virgin and mother of the founders of Rome.