The 12th-century Doppelkirche Schwarzrheindorf is a magnificent ‘double church’ where the nobility sat on the upper level and the parishioners on the lower. The beautiful Romanesque architecture is impressive, as is the restored Old Testament fresco cycle in the lower church. It's across the river from Poppeksdorf in the suburb of Schwarzrheindorf; take bus 550 or 640 from the Hauptbahnhof to Schwarzrheindorf-Kirche.