The Taj Mahal is considered the pinnacle of Mughal architecture, a style that combines Islamic, Persian, and Indian elements. Commissioned in 1632 by Emperor Shah Jahan as a mausoleum for his favorite wife, Mumtaz Mahal, it took 20,000 artisans over 20 years to complete. The structure is famous for its perfect symmetry; the only asymmetrical element in the entire complex is the tomb of Shah Jahan himself, which was placed next to his wife's after his death. The white marble walls are decorated with 'pietra dura'—an intricate technique of inlays using semi-precious stones like lapis lazuli, jade, and crystal to form floral patterns. The central dome is a 'double dome,' a feat of engineering that allows the interior ceiling to be at a lower, more intimate height while the exterior dome towers majestically over the landscape.