Bourges Cathedral is notable for the simplicity of its plan, which did without transepts but which adopted the double-aisled design found in earlier churches such as the Early-Christian basilica of St Peter's in Rome or in Notre Dame de Paris. The double aisles continue without interruption beyond the position of the screen (now largely destroyed though a few fragments are preserved in the crypt) to form a double ambulatory around the choir. The inner aisle has a higher vault than the outer one, while both the central nave and the inner aisle have similar three-part elevations with arcade, triforium and clerestory windows; a design which admits considerably more light than one finds in more conventional double-aisled buildings like Notre-Dame. This design, with its distinctive triangular cross-section, was subsequently copied at Toledo Cathedral and in the choir at Le Mans.