The Old Treasury, Melbourne and a clue.

The Old Treasury Building was constructed during the Victorian Gold Rush to house the (then) colony's gold vaults.

The building once housed the Treasury Department Victorian Government, but is now a museum focussed on Melbourne history

Built between 1858-62 the building was designed by an architect called J. J. Clark who was just 19 years of age!

I will post an answer to yesterday's What is it Wednesday tomorrow. A clue, Kitty and Linda G are half right.