The Taj Mahal of Agra is one fine example of how to plan and then successfully apply symmetry into the proceedings. Every inch of Taj Mahal is a breathing example of it, except for one thing: the cenotaph of Shah Jahan himself, which appears to be an afterthought as it was added much later and disassembles the symmetry of the burial chamber as it is bigger in size when compared to the cenotaph of Mumtaz Mahal. Ever wondered why is this the only dissymmetrical thing in the entire Taj complex? Some scholars believe that Shah Jahan had never meant for himself to be buried along with his wife but was planning something big. Something that if was seen in actuality, would have been literally beyond the scope of words, and would have put other monuments to shame. Scholars believe this "something big" to be another Taj Mahal, but built in black marble instead of white.
According to the Black Taj myth, Shah Jahan had planned to build mirror image of the Taj Mahal he built for Mumtaz, albeit in black, on the other side of the river and connect the two by a bridge. This Black Taj was to be dedicated to Shah Jahan himself. A European traveler by the name of Jean Baptiste Tavernier who visited Agra in 1665 first mentioned the idea of Black Taj in his fanciful writings. And considering Shah Jahan's obsession with symmetry, the idea certainly seems plausible. More credibility to the story is added by an observation made by archeologists in 2006, when they reconstructed part of the pool in the moonlit garden and it reflected a dark reflection of the white mausoleum. The writings of Tavernier mention that Shah Jahan began to build his own tomb on the other side of the river but could not complete it as he was deposed by his own son Aurangzeb.
Fuel to the fire is further added as some scholar suggests that the blackened marbles in Mehtab Bagh that lie on the other side of the river are actually grim remains and foundations of an abandoned plan. On the other hand, other section of scholars totally dismiss the theory of Black Taj as it was discovered that the black marble remains in the Mehtab Bagh are not natural black but have become black over the course of time due to staining and wear and tear. Also, Mehtab Bagh was built by the first Mughal Emperor Babur, years before construction of Taj Mahal even started. The theory is once again dismissed by some scholars who believe that if Shah Jahan wanted to build a Black Taj Mahal, he would have started working on it immediately after completion of the first Taj Mahal in 1653, after which he had 5 years before he got arrested. While historians continue to argue over it, the idea of a Black Taj standing in front of the White Taj certainly keeps the anticipations and imaginations on a high.