Origins and architecture of the Taj Mahal leading classes of Indian social structure and thus defined themselves as rulers in Indian terms. Red sandstone also had significance in the Persian origins of the Mughal empire where red was the exclusive colour of imperial tents. In the Taj Mahal the relative importance of each building in the complex is denoted by the amount of white marble (or sometimes white polished plaster) that is used. The use of naturalist ornament demonstrates a similar hierarchy. Wholly absent from the more lowly jilaukhana and caravanserai areas, it can be found with increasing frequency as the processional route approaches the climactic Mausoleum.
Taj Mahal mausoleum was essentially completed in 1643 but work continued on other phases of the project for another 10 years. The Taj Mahal complex is believed to have been completed in its entirety in 1653 at a cost estimated at the time to be around 32 million rupees, which in 2015 would be approximately 52.8 billion rupees (U.S. $827 million). The construction project employed some 20,000 artisans under the guidance of a board of architects led by the court architect to the emperor, Ustad Ahmad Lahauri. The Taj Mahal was designated as a UNESCO World Heritage Site in 1983 for being