The Romanesque keep is located in immediate proximity to the Brömserburg. The structure suggests origins from the 9th century through its forms. At 38 meters tall, the tower of the Boosenburg surpasses all other buildings in the city. A castle-like residential building hugs its walls, which are up to three meters thick.
The name Boosenburg goes back to the noble family of Boos von Waldeck, who acquired the castle in 1474. Even today, the coat of arms of the Boos family serves as the coat of arms of the castle.   
Today, the keep, which was renovated in 1991 and is no longer accessible, sits picturesque amid a vineyard. Together with other magnificent manors of the Lords of Rüdesheim, a whole noble quarter had formed at this site. These lords were ministers of the Archbishopric of Mainz and benefited from the favorable location of the city. Rüdesheim and Bingen were significant cornerstones of the Electoral Mainz power in the Rheingau and still today form the gateway to the Upper Middle Rhine Valley. The customs station and the ferry landing are also suspected to be in close proximity to the Boosenburg.
Today, the Rüdesheimer Hildegardweg offers a view of the still-preserved keep: The hiking path runs directly past the facility.