The story is much more interesting than any other Treasure hunt stories , it goes like this. The wealthy Nawabs were constantly under threat from the British and they were so keen on the Treasure. The treasure was so big that the entire Hindustan(India) could have been made rich. The Brits were able to bribe the King's Maid without him the King won't go out, as it was the maid's duty to provide with the royal footwear. And when they attacked the King didn't get up from his Throne and he knew they were coming. He could have gone into the Labyrinth in the walls which is way complicated and were the attackers will be lost their way, but he didn't. He sat there but to keep the Khazaana(treasure) safe, he had thrown the Key into the Bauli. It was so deep that the key was never found even though the King was captured. Till date the Treasure is undiscovered.
There is also a tunnel which provided access to various parts of the country. It is the route used by the Nawabs to transport weapons and other material to nearby kingdoms like Agra, Delhi etc. Having lost the key, the Brits entered the tunnel in search of the Treasure and nobody ever returned from it.
(b) Bhool bhulaiyya (Labyrinth) : This is the main wonder of Bara Imabara. It is a maze between the inner and outer walls of the Main building. From outside it looks like a normal building. But it is built in such a way that any outsider will definitely get lost and will be running around circling the inner wall. The entire construction is done with Lime stone and it also included common wheat grains, sugar cane, various pulses etc. And surprisingly no metal or wood were used in the construction. The building has complete openings everywhere for ventilation but nobody can see from the outside. Only those who are inside can see that too even the entrance of the complex. You will be shocked to see the wonders in this building alone.
The phrase "walls have ears" is believed to be originated from this Imambara. As the walls of this building are acoustically finished in such a way that even the whispers are heard far across the walls. Without even seeing the person who is murmuring, we can hear the sounds. And the Echos are completely shadowed except for the center of the walls. At one particular point you can hear the sound of a matchbox being lit from across the room.
5. Chota Imabara:
Chota imabara is though small in size, holds a key to number of ancient technology. this building flaunts its name for being created India's first Wind Gauge, First Lighting arrest and making use of first Geyser setup for warm water and First Shower.