Shahjahanabad and Red Fort
Agra, which first became the capital of Sikandar Shah Lodi was enlarged by Akbar but was enriched by Shah Jahan. But, one more splendor of Shah Jahan was the Shahjahanabad, the celebrated Purani Delhi. It began in 1638-39 and was completed in 1648. This 1500 acre city was like a quarter circle with Red Fort (originally named Quila-i-Mubarak) in the middle of it, which remained the Capital of the Mughal emperors till the empire was swept out by the British. It was used by the British as a military camp till 1947. Once Shahjahan moved to Shahjahanabad, the grandeur and splendor of Agra was eclipsed.
The Red Fort was the most magnificent royal residence of the world. But when it was occupied by Bahadur Shah Zafar, the last of the Mughals, the Mughal empire was confined to this fort only.
In 1656, the Jama Masjid at Delhi was completed which is even today the largest mosque of India. This was the most magnificent among the mosques built by Shah Jahan in Delhi, Agra, Ajmer and Lahore. Its floor plan was based upon the Mosque at Fatehpur Sikri, but the size was bigger. It was raised on a rocky basement and had 3 domes and two lofty tower 130 feet high.