Though the legend tells that it would have been planted the year Normandy was created, in 911, scientists believe that the oak of Allouville was contemporary of Charlemagne in the 9th century. In the 19th century, its bark was patched with traditional wooden shingles as it was leaking. The tree shelters two natural vaults formed within its imposing trunk of 52 ft (16 m) in diameter for 59 ft (18 m) in height. A metal structure has supported it since 1988, as the second chapel is accessed via a spiral staircase. The top of the tree is adorned with a large cross.