The Taj Mahal incorporates and expands on design traditions of Persian and earlier Mughal architecture. The tomb is the central focus of the entire complex of the Taj Mahal. It is a large, white marble structure standing on a square plinth and consists of a symmetrical building with an iwan (an arch-shaped doorway) topped by a large dome and finial. Like most Mughal tombs, the basic elements are Persian in origin.