The great abbey church that William the Conqueror founded in 1063 as penance for his marriage to his cousin Matilda — the Pope had declared the union uncanonical — is one of the finest examples of Norman Romanesque architecture in France. The twin-towered west facade, completed in stages over the 11th and 12th centuries, is austere and powerful in a way that Gothic cathedrals rarely are.
The abbey buildings behind the church now serve as the Caen town hall, which means access is sometimes limited, but the church itself is almost always open. The interior is plain — the Romanesque instinct for unornamented stone — but deeply impressive in scale. William's tomb is in the choir. Guided tours are available that take in both the church and the abbey buildings, including the cloister and the monks' refectory.