Commenced in 1849 and completed in stages in 1851, 1853, 1900 and 1919 in the Victorian Neo-Classical and Italian Palazzo styles by NSW Colonial and Government architects Mortimer Lewis, Edmund Blacket, Walter Liberty Vernon, and George McRae, the building has been used variously by the NSW Treasury, the Audit Office, the Premier's Department, the Police Department, and the Ministry of Transport.

The Bridge Street wing was altered and extended for the Premier's Department in 1916–1919, to the design, as modified, of the then Government Architect George McRae.

The facade of Lewis's original building in particular is a premier example in NSW of 19th century "Italian Palazzo" style based closely on a London model.

The bold but sympathetically related Vernon additions fronting Macquarie Street are impressively proportioned and detailed and represent an excellent and perhaps unique example of late Victorian eclectic architecture in NSW.

Historically the building group is significant because of its long association with the NSW Treasury and the state treasurer's and premier's offices.

[1][4] Treasury Building, Sydney was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

Historically the building group is significant because of its long association with the NSW Treasury and the state treasurer's and premier's offices.

The facade of Lewis's original building in particular is a premier example in NSW of 19th century "Italian Palazzo" style based closely on a London model.

The bold but sympathetically related Vernon additions fronting Macquarie Street are impressively proportioned and detailed and represent an excellent and perhaps unique example of late Victorian eclectic architecture in NSW.

The facade of Lewis's original building in particular is a premier example in NSW of 19th century "Italian Palazzo" style based closely on a London model.