In the seventeenth century the post office's letter office had followed the commercial centre of the city from the Dublin Castle area further west to a building in High Street backing onto Back Lane in 1668 and then to Fishamble Street, on the western border of Dublin 2 during the reign of Charles II.

Around 1709 the letter office had moved closer to College Green, to Sycamore Alley, parallel to Crane Lane, known as Old Post-Office Yards.

The move to the heart of Dublin 2 in College Green, opposite the Irish Parliament House that became the Bank of Ireland in 1803, took place in 1771 but proved to be too small for the expanding mail demands even with renting more buildings in Suffolk Street over time.

Staff complained about the work conditions there over its 42-year use, because of space constraints, the roof leaking tar due to the summer heat and rain in winter on workers below, paper dust, etc., such that the subject was raised in Dáil Éireann on a number of occasions.

[23][24][25][26] The sorting office had direct access to Westland Row station where trains departed to connect with the Dun Laoghaire to Holyhead mail boat for onward transmission to Great Britain and foreign destinations.

It was eventually closed in August 1967 when a new sorting office opened in Sheriff Street with direct access to Connolly station.

[30] Five years after the establishment of the state, in 1927, the Department of Posts and Telegraphs initiated a scheme that requested senders to add a code to each address in Dublin City and suburbs.

It is a seven-bay four-storey building with granite cladding and extensive windows with strong horizontal features had been influenced by modernist architecture.

It is listed as a protected structure and was sold in 2022 for €9.5 million and, under a 25-year lease, An Post have retained the ground floor and part of the basement.