The Bara Imambara — literally "the Great Imambara" — is the single most important monument in Lucknow and the building that defines the city's Nawabi identity. Asaf-ud-Daula commissioned it in 1784; the architect, Kifayat-ullah, designed a central hall of 50 by 16 metres that for over a century held the longest unsupported vaulted ceiling in the world. There are no beams, no columns, and no European-style trusses: the entire span is held up by a sophisticated system of interlocking brickwork.
The complex contains the Asafi Mosque, the stepped Shahi Baoli (a baori-style stepwell that was once filled with running water from the Gomti), and the famous Bhool Bhulaiya — a maze of more than a thousand interconnected passages in the upper levels of the imambara walls. Take a guide, do not wander the maze alone, and visit early before the heat and the crowds make the corridors close in.