It was designed by the New South Wales Colonial Architect's Office under James Barnet and later Walter Liberty Vernon, and was built by William Farley.

It was the first of the early Sydney suburbs that was not self-sufficient - its inhabitants, unlike those of Balmain or Newtown, where work was available in local industries, had to go away each day to their places of employment.

John Palmer, the settlement's commissary, refused to allow people to cross his land grant ('Woolloomooloo'), so the road had to follow a roundabout way through Paddington to bypass his 40 hectares (100 acres).

[3] From 1848 when Victoria Barracks had been opened (designed by Lt.-Col.George Barney) and homes for the soldiers and their families had been erected, Paddington began to assume a real identity...The (barracks site) land was sandy - in fact a huge sandhill was located on the western side of the Greens Road area, and the foundation trenches had to be dug very deep, to locate firm stone for the foundations.

[3] It is hard to imagine that in 1822 the mansion Juniper Hall (the opposite southern corner of Oxford Street from the Reservoir site) stood alone, without the many neighbours it has today.

Juniper Hall was built for Robert Cooper, distiller and emancipist merchant, who with partners James Underwood and Francis Ewen Forbes, had received 100 acres from Governor Brisbane in c.1818, covering the whole of north Paddington, and they agreed to erect 3 mansions and a distillery there.

The bazaar, which has operated since the mid 1970s, draws visitors from all over the city and has contributed to Paddington's development as one of Sydney's favourite tourist spots, along with Bondi Beach and The Rocks.

[3][5] The first official postal service in Australia was established in April 1809, when Sydney merchant Isaac Nichols was appointed as the first Postmaster in the colony of NSW.

The current site on the corner of Oxford and Ormond Streets was secured on 27 February 1882; and plans drawn up during 1884 under the supervision of the New South Wales Colonial Architect James Barnet in the Victorian Italianate style and was officially opened on 26 December 1885 (1885-12-26).

The predominantly two-storey building is constructed of ashlar and smooth rendered bricks, with a three-storey stair tower and upper floor to the western end of the southern facade.

[3] The appointment of James Barnet as Acting Colonial Architect in 1862 coincided with a considerable increase in funding to the public works program.

The post offices constructed during this period were designed in a variety of architectural styles, as Barnet argued that the local parliamentary representatives always preferred "different patterns".

Vernon is also attributed in having designed the building,[2] however, given the timeframe, it is likely that his contribution related to minor additions and alterations[3] in the Victorian Free Classical style.

[3] Paddington Post Office is a predominantly two-storey ashlar and smooth rendered brick building in the Victorian Italianate Style, with a three-storey stair tower and upper floor to the western end of the southern facade.

There is a brown tiled recessed side porch containing the post boxes enclosed by a lockable, grey painted wrought iron palisade fence and gate.

There is a large British Coat of Arms located to the centre of the Oxford Street facade parapet, resting upon a continuous dentilled entablature with dark trims.

Air conditioning vents are located to the ceiling of the retail area, there is exposed ducting to the mail room and there are attached and suspended banks of fluorescent lights to the ground floor spaces.

The flooring is mainly sheet vinyl, however some carpeting is present in the large southern mail room and there is tiling to the modern bathrooms.

[3] The first-floor ceilings are mainly mini-orb, painted cream, with large circular perforated vents and an ovolo mould cornice.

Skirting is plain, with some quad mould strip used and original remnants to the small store rooms, hall and main stairwell.

[3] The only outbuilding to Paddington Post Office is the c. 1979 detached cycle shed located to the northwestern corner of the site in the concreted rear yard, and there is a projecting brick dock to the western boundary.

The Post Office retains the features which make it culturally significant, including architectural details such as the classical front porch with fluted columns, central pediment, and parapeted roof, and its overall form, corner position and style.

By this time it is evident that the residence in the Ormond Street section had been converted to use by the Post Office and the northernmost addition of a kitchen, laundry and servants room had been demolished to create the current laneway.

[3] Some notable features of the building include the classically designed arch over the base of the ground floor main stair, and the original or early timber and etched glass entry doors to the retail area in very good condition.

An intrusive element to Paddington Post Office is the exposed air conditioning ducting to some ground and first-floor interior spaces.

Overall, the building retains an ability to demonstrate aspects of its original function and layout, with the former residence component to Ormond Street being particularly readable in the context of the site.

Architecturally and stylistically, elements of note include the tower base in the west bay (without the tower) fronting Oxford Street; the unusually complex composition of the Oxford Street frontage for a medium sized suburban post office; the open-bed pediment ‘driven’ by an extruded voussoir below the intended tower layers which was unusual at this time, being more associated with 1900s Baroque revivalism as seen at Ipswich in Queensland; and the elevated entrance in a three-bay recessed arcade (loggia) fronted by four columns in antis, flanked by a rusticated ground floor wall framed with pilasters.

The building is also aesthetically interesting on a number of levels – it is considered to be one of James Barnet’s more eclectic designs, bringing a series of his other genres together and introducing some oddities.

Other unusual details include the widely spaced dentil brackets and the spur entablatures suggested in the ground floor frieze.

While the pair of historic two-storey terrace dwellings with cantilevered balconies (located to the north of the post office) appear to be on title, these have not been investigated in details and no assessment of their significance is made.