Zamzama gun
It is placed at Istambul chunk Mall road, near to Anarkali Bazar and Lahore Museum. It is also known as Bhangia wali Toop because it was under the possession of Bhangies for years. It is also regarded as Talisman of Supremacy, as whoever got it also got power and victory during battle. 
It was built by Shah Nazeer at the order of Shah Wali Khan, the minister of Ahmad Shah Durani the Abdali king in 1757 A.D. Ahmad Shah Durani used it the war of Panipat in 1761 A.D.  It remained under the possession of Bhangies for years and in 1802 A.D. Ranjit SIngh captured it after expelling Bhangies from Amritsar. 
In 1818 it was removed to Lahore as it was unfit for use because of being seriously injured. and was placed at Delhi Gate Lahore until 1870 A.D. 
in 1870 A.D. it was placed at the present location where now it is present.