

The building was built in a famine relief program in 1784 by Nabab Asaf-ud-Daulla. (In Lucknow)
The Great Imambara or the Bada Imambara has a central hall, one of the largest vaulted galleries in the world, beneath which many underground passages are present. Any pillars or any other supports do not support the main hall, which is over 50 feet in height. The roof has been put together with interlocking bricks without using a beam or a girder. Hence, it is viewed as a unique achievement of architecture.
There are eight surrounding chambers built to different roof heights, permitting the space above these to be reconstructed as a three-dimensional
labyrinth with passages interconnecting with each other through 489 identical doorways. This part of the building, known as is a popular attraction, and often the whole complex may be referred to as the
bhulbhulayah. It is possibly the only existing maze in India and came about unintenionally to support the weight of the building, constructed on marshy land.
There is also a blocked (tunnel)passageway which, according to legends, leads through a mile-long underground passage to a location near the
Gomti river. Other passages are rumoured to lead to
Faizabad (the former seat of power of the Nawabs), Allahabad and even to Delhi. They exist but have been sealed after a period of long disuse as well as fears over the disappearance of people who had purportedly gone missing, while exploring.