So called because the mountains look blue, in the splendid clear skies of Australia. This picture shows why.

The Blue Mountains form the boundary between the fertile and densely populated coastal strip (which includes places like Sydney) and the vast, arid interior of the continent where there is so little rainfall that very little life can be sustained.

Typical of the rugged terrain on the border of the outback, these rock formations have been colonised by tough trees which are sufficiently deep rooted to deal with the lack of rainfall.

The fort in Sydney Harbour was built to guard the harbour mouth against attack or invasion. It must have been a grim posting for the soldiers assigned there.