triforium

A gallery of arches above the side-aisle vaulting in the nave of a church.

In medieval architecture, a gallery above the arches of the nave and choir, and often of the transepts, of a church, generally in the form of an arcade.

The gallery or open space between the vaulting and the roof of the aisles of a church, often forming a rich arcade in the interior of the church, above the nave arches and below the clearstory windows.

The gallery of arches above the side-aisle vaulting in the nave of a church.