If truth be told, more has vanished than remained of this site, where monks allegedly found King Arthur and Queen Guinevere's graves in the 12th century. (No evidence suggests either Arthur nor Guinevere have ever really existed of course.)
The abbey had been founded way before that (7th century!) and persisted until Henry VIII saw no other way but to divorce first the Pope and then Catherine of Aragon, in the early 16th century.
Despite the sorry state of the abbey, enough is left to allow you to glimpse the past splendour. The spiritual presence of the Round Table and the swarms of hippies around the abbey and the rest of the town rather added quaintness to the general impression of otherworldliness.