I was about to take a photograph of this cannon (two "n"s) when these two wandered up and beat me to it. Eh, {shrug}, fair enough; you two can both be my subject as well, then.
The cannon itself was part of Wollongong' Harbour's defences against... whoever the bad guys were at that time and possibly the Klingons as well... back in 1880. The guns fired a 31kg (about 68 pounds, for old artillery types) solid shot to a range of 1.6km (a mile, give or take). They were manned by volunteers, and taken out of service in 1900. In 1959 the guns were recovered and preserved at the Army Reserve and Naval Cadets depots before being restored and relocated by Wollongong Council in 1983.