St. Gereon's Basilica

St. Gereon's Basilica is one of the great Romanesque churches of Cologne, distinguished by an extraordinary oval domed hall unlike any other north of the Alps. Its core grew from a late Roman burial chapel, and the towering ribbed decagon was added in the thirteenth century over the ancient walls. Dedicated to a Roman soldier martyred with his companions, the church retains early mosaics and medieval wall paintings in its crypt and choir. The dramatic ribbed vault soaring above the decagonal nave is a feat of medieval engineering.