Also known as the Bara Imambara, it was built by Nawab Asaf-ud-Daula in 1784 and is one of the architectural wonders of that era. Its central hall is said to be the largest vaulted chamber in the world. Except for the galleries in the interior, there is no woodwork in the entire structure. It has large underground passages which have been blocked up.

A staircase from outside leads to a series of labyrinths known as Bhool-Bhulaiyan which is a complicated entanglement of zig-zag pass. Visitors are advised to visit only with authorized guides. Within the compound of the Imambara is the grand Asafi Mosque. Shahi Baoli is another attraction here.