Short answers, pulled from the story.
Construction of Lalbagh Fort was started by Prince Muhammad Azam Shah, the third son of Mughal Emperor Aurangzeb, in 1678 during his time as viceroy of Bengal. After he was recalled by his father, Shaista Khan, the subahdar of Bengal, oversaw the work but also left it incomplete.
Construction halted after the death of Shaista Khan's daughter, Iran Dukht Pari Bibi, in 1684. Shaista Khan came to believe the fort brought bad omen following her death and stopped all work on the structure.
Pari Bibi, the daughter of Shaista Khan, is buried inside Lalbagh Fort. Her tomb occupies the centre of the complex, flanked by the Diwan-i-Aam and the mosque. The inner walls of her tomb are lined with white marble.
The fort was originally called Fort Aurangabad, after the neighbourhood named for Emperor Aurangzeb. The area was renamed Lalbagh in 1844, and the fort took on its current name at that time.
Excavations between 1994 and 2009 revealed that the fort's main walls extended eastward beneath Shaishta Khan Road, suggesting the existing complex is only half the size originally planned by Prince Azam. Archaeologists also found an underground room beneath the bathhouse with terracotta pipes designed to supply hot and cold water.
The three central buildings are the Diwan-i-Aam (the governor's two-story residence), the Tomb of Pari Bibi, and a three-domed mosque. A water channel with fountains connects all three structures across the complex.