Taj has seventeen basement chambers laid out in a line on the side of the and can be accessed using the two staircases on the northern side of the red sandstone pedestal of the Taj. The rooms and corridor made of brick and plaster and have been adorned with stucco and paintings. However, the doors on the extreme points of these basement chambers sunk in the northern wall have been blocked up permanently with thick masonry instead of housing customary crypt containing the third and the real set of graves like those of Turks and Mughals in those days. This custom has been used in the tomb of Iltutmish at Delhi, the tomb of Akbar and the tombs of Itmad-ud-Dauhlah and Chini-ka-Rauza at Agra, but surprisingly is absent here.
According to the speculation of the scholars, Taj must also have these traditional third set of graves hidden but yet existing somewhere in these underground vaults. And assuming they are there then there must also be the doors in the basement corridor to enter those underground arrangements of chambers and corridors. However, since the doors have been blocked impregnably, no further research of the matter is possible and this mystery will remain a mystery forever.
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