The center of the tomb  is called the main chamber.  In the middle of this chamber is the tomb of Mumtaz Mahal and to one side is the tomb of Shah Jahan.  These tombs are not the real ones.  The real ones are buried in a crypt underneath the main chamber.
     The main chamber of the Taj Mahal is an octagonal shaped room.  It is surrounded by eight empty chambers, four rectangular and four eight-sided ones.  These help support the heavy marble dome.  Each of these chambers are outlined with bands of inlaid calligraphy.  Passages from the Koran are also found here.  Flowers in vases are also etched on the walls.
     When the tomb was first built, a gold screen was placed around the cenotaph of Mumtaz Mahal.  In 1643, Shah Jahan ordered that it be replaced with a marble one.
     Four different types of artistic designs was used in decorating the monument. Pietra dura was a technique that was done by precisely carving hard and semi-hard gems, then laying them in sockets of prepared marble.  In the Taj Mahal these designs for the arabesque floral tendrils which cover the surface of the white marble.  A tradition of hardstone carving existed in India for years.  This is seen in places in the Taj Mahal where the carving is done directly on the marble.  The verses from the Koran were inscribed using calligraphy.  In the Taj Mahal the writing includes an optical trick.  The size of the letters over the arch seem to be the same from top to bottom.  This was done by heightening the letters as the distance from the eye increased.  In the mosque, the art of incised painting was used.  This is done by first painting a surface, then scraping a design.  Usually red and white paint were the colors used.
     When visitors enter the Taj Mahal, it is Indian custom to remove your shoes.  This shows respect for the holy places.  The interior is also very dimly lit.  The chambers on both levels are fitted with panes of milky glass.  This gives a diffused light which changes the atmosphere.  This altered light offers a mysterious quality to the inside.  The light changes throughout the course of a day.