The tower of Boosenburg Castle (Oberburg Castle) not only dates from the 9th century but is also the town’s tallest building. The Romanesque keep lies almost directly adjacent to Brömserburg Castle.
As a still visible testimonial to the epoch of the lords of Rüdesheim, Boosenburg Castle, watches over the historical city on the Rhine on the western side. The bergfried, which is no longer accessible and was refurbished in 1991, stands in the middle of a vineyard. Together with other, grand courts of the lords of Rüdesheim, an entire noble quarter had been built up on this site. These lords were ministeriales of the Archbishopric of Mainz and they benefited from the convenient accessibility of the city. Rüdesheim and Bingen were major cornerstones of the power of the Electorate of Mainz in Rheingau and still today form the gate to the Upper Middle Rhine Valley. The customs office and ferry dock were presumably in direct proximity to Boosenburg Castle. Today the Hildegard of Bingen Trail in Rüdesheim affords a view on the still preserved bergfried: the hiking path leads directly past the complex.