Three entries with the name Ancient Chapel.
Ancient Chapel
In the churchyard of this “old and ancient” chapel were the twelve graves of Canaans brothers. On each grave laid a sword.
Ancient Chapel
An old chapel to which Gawain and Hector came.
Ancient Chapel
A chapel near Salisbury where Arthur was taken after the final battle with Mordred. From there, Arthur departed on the sea with Morgan le Fay.
Sir Girflet later found Arthur’s “tomb” there, but it contained only his helmet. Girflet retired there as a hermit. In the Vulgate, Griflet and Lucan were the only warriors to survive the battle of Salisbury, and they took their wounded King to the Ancient Chapel. Griflet is the one who throws Excalibur into the lake.
See also
Black Chapel | The Legend of King Arthur
Source
Post-Vulgate Mort Artu | 1230-1240