[1] The use of Mansard roofs on central and end sections set slightly forward of the main walls add a French Second Empire flavour.

[8] The 1861 design consisted of two storeys, taking up the full site, with a main floor fronted by arcades raised up on a stepped plinth (possibly due to the frequent flooding of Elizabeth Street), mansard roofed end and central pavilions, and a corner clocktower.

It was constructed with bluestone from Brunswick quarries, and sandstone from Tasmania for the facade, including the Doric and Ionic columns.

His plan was later modified by architect John Smith Murdoch of the Commonwealth Department of Works and Railways, and finally completed in 1919.

In 1993, the closure of the Melbourne GPO was first announced and various commercial schemes proposed amid some controversy, but none proceeded until 2001, when it was leased to developers for conversion into a shopping centre, with contemporary extensions to the still incomplete north end.

[14][15] The redevelopment proceeded as planned, including the restoration of the postal hall, and a contemporary styled extension, reopening in late 2004 as a high-end fashion retail precinct.

Cafes occupied the delivery laneway on the east side, and part of the outer colonnade, while the hall itself was subdivided with glass walls into retail tenancies.

The GPO was redeveloped again, reopening on 5 April 2014 occupied almost entirely by Australia's first branch of Swedish retail giant H&M, with crowds forming hours in advance.