The 130 year old secret passage, known as 'Nizam's Bunker' was built by Nizam VI, Mir Mahboob Ali Khan. From Home Science College, it leads to Mint Compound and secretariat and was constructed by East India Company owned Allwyn Company. In a secret passage leading to Mint Compound and Secretariat, the bunker contains valuable treasure chests of the Nizam.

The passage at the Home Science College leading from it belongs to the British era and the entrance doors were built by Allwyn of the East India Company. The walls are made of limestone and are still intact. The walled passage was used as an escape route from the college in case of an attack by enemies or as a rest house when it was too hot outside. The passage was filled with mud, slush and stagnant water. The bunker receives light and air from two pillar-like structures that have hollow ends and are hidden by leaves hanging from a tree making the pillars difficult to spot.

The door to the ancient Nizam's bunker in the Home Science College has now been opened by the archaeological department. The treasure chests that have been found in this passage will soon be opened. Expert locksmiths from Godrej are to be summoned on Saturday to open the sealed chests. The state archeology director, Prof P. Chenna Reddy, says the chests will soon be removed from the bunker.