The mysterious door of the Taj Mahal is located on the southern side of the structure, and it has been the subject of important enterprise and debate over the times. The door itself is made of solid iron and is speckled with harpoons. It's also said to be connected to a secret chamber within the Taj Mahal, which has noway been opened or explored. The origin and purpose of the mysterious door are shrouded in riddle. Some believe that it was erected as a defense medium to cover the grave of Mumtaz Mahal from raiders. Others suppose that it may have been created to give an escape route for the royal family in case of an exigency.