Interior decoration

The interior chamber of the Taj Mahal steps far beyond traditional decorative elements. Here, the inlay work is not pietra dura but lapidary of precious and semiprecious gemstones. The inner chamber is an octagon with the design allowing for entry from each face, although only the south garden-facing door is used. The interior walls are about 25 metres (82 ft) high and topped by a "false" interior dome decorated with a sun motif. Eight pishtaq arches define the space at ground level and, as with the exterior, each lower pishtaq is crowned by a second pishtaq about midway up the wall. The four central upper arches form balconies or viewing areas, and each balcony's exterior window has an intricate screen or jali cut from marble. In addition to the light from the balcony screens, light enters through roof openings which are covered by chattris at the corners. Each chamber wall has been highly decorated with dado bas relief, intricate lapidary inlay and refined calligraphy panels, reflecting in miniature detail the design elements seen throughout the exterior of the complex. The octagonal marble screen or jali which borders the cenotaphs is made from eight marble panels which have been carved through with intricate pierce work. The remaining surfaces have been inlaid in extremely delicate detail with semiprecious stones forming twining vines, fruits and flowers.
Muslim tradition forbids elaborate decoration of graves and hence Mumtaz and Shah Jahan are laid in a relatively plain crypt beneath the inner chamber with their faces turned right and towards Mecca. Mumtaz Mahal's cenotaph is placed at the precise center of the inner chamber on a rectangular marble base of 1.5 metres (4 ft 11 in) by 2.5 metres (8 ft 2 in). Both the base and casket are elaborately inlaid with precious and semiprecious gems. Calligraphic inscriptions on the casket identify and praise Mumtaz. On the lid of the casket is a raised rectangular lozenge meant to suggest a writing tablet. Shah Jahan's cenotaph is beside Mumtaz's to the western side and is the only visible asymmetric element in the entire complex. His cenotaph is bigger than his wife's, but reflects the same elements: a larger casket on slightly taller base, again decorated with astonishing precision with lapidary and calligraphy that identifies him. On the lid of this casket is a traditional sculpture of a small pen box. The pen box and writing tablet were traditional Mughal funerary icons decorating men's and women's caskets respectively. The Ninety Nine Names of God are to be found as calligraphic inscriptions on the sides of the actual tomb of Mumtaz Mahal, in the crypt including "O Noble, O Magnificent, O Majestic, O Unique, O Eternal, O Glorious... ". The tomb of Shah Jahan bears a calligraphic inscription that reads; "He traveled from this world to the banquet-hall of Eternity on the night of the twenty-sixth of the month of Rajab, in the year 1076 Hijri."