text: how old tajmahal is?   in december 1631, the fifth mughal emperor, shah jahan, commenced the construction of one of the greatest monuments of all time, the taj mahal. it is a mausoleum built in the memory of his beloved and favorite wife, mumtaz mahal, fulfilling one of the promises that he made to her as she lay on her deathbed:  to erect a monument to match her beauty.