Rheasilvia is the most prominent surface feature on the asteroid Vesta and is thought to be an impact crater. It is 505 km (314 mi) in diameter, which is 90% the diameter of Vesta itself, and is 95% the mean diameter of Vesta, 529 km (329 mi). However, the mean is affected by the crater itself. It is 89% the mean equatorial diameter of 569 km (354 mi), making it one of the largest craters in the Solar System, and at 75°S latitude, covers most of the southern hemisphere. The peak in the center of the crater rises 20–25 km (12–16 mi) from its base, the tallest mountain known in the Solar System.

Rheasilvia was discovered in Hubble Space Telescope 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.

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