The Cathedral Excavations Museum under the Residenz- and Domplatz gives visitors a fascinating view of building work since the Roman Age in the area of today’s cathedral.
Particularly impressive are the excavation finds of a Roman villa built in the late second/early third century over the remains of an older house and aligned along a road leading south. Visitors can see extensive parts of the former central residential area, a columned interior courtyard, corridors, and rooms with drainage and warm air-heating systems. There are mosaic floors of outstanding quality, in part superimposed one above the other in two layers.
Also interesting are the medieval foundations and the masonry work for the west tower of the Late Romanesque cathedral, which was built from 1181 on under Archbishops Conrad III (1177–1183) and Adalbert III (1183–1200), and demolished by Archbishop Wolf Dietrich (1587–1612) after a fire in 1598. The present-day cathedral is Early Baroque and was consecrated in 1629.