The tomb Base 
Main arch and side pishtaqs
The focus of the Taj is the white marble tomb. Like most Mughal tombs, the basic elements are Persian in origin: a building with arched entrances, topped by a large dome. In India, and most especially at the Taj, this simple idea reached its zenith.
The tomb stands on a square plinth. The base structure is a large, multi-chambered structure. The main chamber houses the cenotaphs of Shah Jahan and Mumtaz (the actual graves are a level below).
The base is essentially a cube with chamfered edges, roughly 55 meters on each side (see floorplan, right). On the long sides, a massive pishtaq, or vaulted archway frames an arch-shaped doorway, with a similar arch-shaped balcony above. These main arches extend above the roof the building by use of an integrated facade.
To either side of the main arch, additional pishtaqs are stacked above and below. This motif of stacked pishtaqs is replicated on the chamfered corner areas.
The design is completely uniform and consistent on all sides of the building. Four minarets, one at each corner of the plinth, facing the chamfered corners, frame the tomb.