Original: A dark albedo feature about  across has been named Olbers in honour of Vesta's discoverer, but it does not appear in elevation maps as a fresh crater would, and its nature is presently unknown, perhaps an old basaltic surface.
Simplified: A dark feature about 200 km across has been named Olbers in honour of Vesta's discoverer, but it does not appear in elevation maps as a fresh crater would, and its nature is presently unknown, perhaps an old basaltic surface.