MonoMonday: Openings

Today's Shape and Form in the Landscape theme is Openings.
After visiting Helen in hospital this morning Mr isbi and I went for a drive to the old gun emplacements and tunnels at Middle Head. These fortifications were first established at the time of the Crimean War and used during WW1, WW2 and the Vietnam War.

The main blip was taken at the opening of one of the tunnels. 
If it's not outdoors enough for the theme, the first extra shows one of gun emplacments and in the background is the opening to Sydney Harbour between North and South Heads.
 
While walking around the Heritage Listed area I took many other blippable shots so will add a few in extras.

Thanks for looking after us this week Pinkhairedlady.