The place name Bibbiano owes its name, by derivation, to the term “bibbio” (lat. bibianum), another name for the wigeon, an aquatic bird that proliferated in these areas. The settlement dates from 850 and was the property of the imperial legate at the time of Ludovico II, Guinigi di Reghinari, a Lombard count: a coat of arms of his family (called Guinigi or Winigi) was found in the oratory of the tower fort, built in the 9th century.
Medieval in appearance with Guelph battlements, it is surrounded on three sides by a moat with a masonry bridge (there was originally a drawbridge) and partial patrol walkway. The walkway remains only on the north side, while in the west corner there is a brick garret, crenellated and rounded on the inner side, which must have been the shelter of the sentinels on guard duty. The southwest and southeast sides are lower and worse preserved: traces of other lost garrets remain in the surviving corner brackets.
Inside is a ring-shaped courtyard, with the keep in the center, connected to the walls by an arched passageway over the inner clearing. Over the arch a walkway supported by corbels leads to one of the two original corner turrets, with rebuilt battlements in the style, which surmounts the northeast entrance portal. The wall bases are slightly scarped, and the keep has a cornice of hanging arches on corbels at first-floor level, supporting the slight overhang of the upper floor. Corresponding to another turret, equipped with a lowered brick arch at the base and a plummet, is the inner gateway of the keep, placed on an axis with the access to the outer walls and elegantly framed by tuffaceous sandstone bosses. The second plumbarium, which towers above it, is a recent reconstruction.
Inside is the Annunciation, the last work of Pietro Lorenzetti, and the Madonna in the castle chapel, by Baldassarre Peruzzi.
