Shah Jahan commissioned the Red Fort (Lal Qila) between 1638-1648 when he shifted his capital from Agra to Delhi. The fort served as the main residence of Mughal emperors for nearly 200 years. Built with red sandstone, it represents the pinnacle of Mughal architecture under Shah Jahan's patronage, who also built the Taj Mahal and Jama Masjid.