Great Gaddesden

Coordinates: 51°47′27″N 0°30′29″W / 51.7909°N 0.508°W / 51.7909; -0.508

Great Gaddesden /ˈɡædzdən/ is a village and civil parish in Dacorum Hundred in Hertfordshire, England. It is located in the Chiltern Hills, north of Hemel Hempstead. The parish borders to Flamstead, Hemel Hempstead, Nettleden and Little Gaddesden and also to Studham in Bedfordshire.

The Church St. John the Baptist was probably the site of a pre-Christian sanctuary. The church shows features of every period since the 12th century. Part of the chancel with Roman bricks dates back to the early 12th century. The old church was extended by the south aisle in the 13th century and the north aisle in the 14th century, the west tower was built in the 15th century and the north chapel in the 18th.

The medieval convent of St Margarets stood northwest of the village. For a while the site served as a WW2 RCAF transit camp and later a boarding school for children with Special needs, and it is now a Theravadin Buddhist monastery, Amaravati Buddhist Monastery, complete with temple.