Its foundations probably date back to the 10th century. Exposed along the city's ramparts, it was rebuilt after the English seats of 1346 and 1417. Ruined in 1944, the building preserved an octagonal lantern-tower from the first half of the 15th century and, standing against the chevet, an equestrian statue from the turn of the 13th century representing Emperor Constantine.
http://www.caen-tourisme.fr/en/discover-caen/religious-heritage/saint-etienne-le-vieux