 Complete the following phrase:  The crossing dome is placed over the meeting point of the transept and the choir, and, like the bell tower, has eight sides. It was constructed beginning in about 1330, following the rebuilding of the transept. Its base is topped by a gallery with pointed arches, beneath a level with large arched bays, two on each side, side, divided by clusters of columns. Above this are blind arcades, an ornate cornice, and then a pointed roof with a pair of dormer or skylight windows, a small window above a large one, on each side, which brought light to the choir below. The medieval crossing domes aspect was altered several times over the centuries. The currently visible, much higher crossing dome was designed in grand Romanesque Revival style by the architect Gustave Klotz, after the original dome had been heavily damaged by Prussian shelling during the 