Here we see 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.

(Harbonnieres, or more correctly accented "Harbonnières" is a commune in the Somme (yes, that Somme) department in Hauts-de-France in northern France . It's about 110 km NNE of Paris.)

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. (That is also near the Somme in north-eastern France, about 11km NE by road from Harbonnieres.) The 15" gun itself was presented by the Australians to the city of Amiens, the region's major city. That was appropriate given that Amiens was this gun's principal target, as I'll discuss in more detail in the next shot.

On the right is the forward gun turret with its 5" gun 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.