OH, HB and sandstone

There aren't all that mny places where you can get the Sydney Harbour Bridge and Opera House in one shot. The Dawes Point (western) side of the bridge is one.

This is taken from Ives Steps Wharf right near Pier One.

I don't know what the little round copper-roofed sandstone building is - couldn't see a plaque (maybe I'm just unobservant), and I've been madly googling, to no avail. So if anyone knows what it is, I'd love to know. It's a footpath level, with the wrought iron fence along the water on either side.

Update: My Sydney bloggy colleague and indefatigable historical super-sleuth, Julie, has probably solved the mystery. The site was originally used as a tiny observatory, built by Lieutenant Dawes. But then Governor Macquarie ordered a crenellated tower be built as a defence against the Russians and French, so this is probably part of it.

Julie also uncovered some interesting information about the beautiful wrought iton balustrade - have a look at Julie's Plumbing the Deeps blog to find out more.