The department has decided to initiate research into the historicity of the gun.
A Mughal-era gun and two cannonballs were found in a vault at the Department of Medieval and Modern History in Allahabad University.
Department head Yogeshwar Tewari told news agency Press Trust of India that the building was being used by Indian Press during the 1857 revolt and the gun might have been hid there at that time.
He said according to a defence expert, the gun belonged to the 15th or 16th century.
The department has decided to initiate research into the historicity of the gun.
Mr Tewari said Sayyad Ali, a peon at the department, knew about the gun for years but nobody believed him.
"After I took charge of the department head, I asked Sayyad Ali to bring the gun. He had kept it safe during the repair of the building," Mr Tewari said.
He said the gun weighed 40 kg while the cannonballs weighed around 20 kg each. The recovered objects will be kept at the department museum.