Mount Enzou - Ryuudou Temple

A mountain located in the southern part of Fuyuki City. Boasts the strongest leylines in the area. Ryuudou Temple is located at the peak, which is the location where the Holy Grail is summoned in the First and Fifth Holy Grail Wars. Underneath the temple there is a giant cavern known as Ryuudou [lit: dragon cave], which is where the the goal of the Holy Grail War, the Greater Grail, is set up.

Fate/Zero Animation Guide II: Glossary of the holy grail war II