Two guns from two different eras.

On the left is a German 28cm (11") railway gun from World War I. It was captured near Harbonnieres, France by the Australian Corps on 8 August 1918.

The metal plate that can be seen just below the gun barrel was made from metal taken from a 15" gun captured near Chuignes on 23 August of the same year. (Both places are near the Somme in north-eastern France.) The 15" gun itself was presented by the Australians to the city of Amiens.

On the right is the forward gun turret (featuring one of two 5" guns) from the former HMAS Brisbane (DDG 41), a Charles F Adams class destroyer. The Brisbane was in service from 1966 to 2001, and was sunk as a dive wreck off the coast of Queensland in 2005. The Brisbane served in both Vietnam, and in the first Gulf War.