According to tradition, Joseph of Arimathea brought the legendary cup called the Holy Grail to Glastonbury.

An excerpt from the article 16 facts about Glastonbury

At the foot of Glastonbury Tor, there is an old well in which the waters of the gushing spring make a sound reminiscent of the beating of a human heart. Because the water contains a lot of iron oxides, it is colored red, which is why it is called the Blood Spring. Most often, however, it is referred to as the Well of the Chalice, because, according to tradition, the Holy Grail was hidden there. The Grail was credited with miraculous properties, and after its disappearance, it was searched in vain by the Knights of the Round Table and King Arthur.