(21) Lutetia is a Main Belt asteroid discovered in 1852 by Hermann Goldschmidt from Paris, France, and named after the Latin name of the city. With an equivalent spherical diameter of about 100 km Lutetia is a comparatively large asteroid and could represent a surviving member of the population of original planetesimals that contributed to the formation of the inner planets. In 2010 Lutetia was visited by the Rosetta spacecraft on its tour to comet 67P Churyumov-Gerasimenko. The close flyby enabled its bulk density to be determined to about 3.4 g cm−3, among the highest densities of asteroids measured so far. The images returned by the spacecraft revealed a body that experienced a complex collisional evolution, with multiple local resurfacing events and a thick regolith layer.