Francis Johnston (1760 – 14 March 1829) was an Anglo/Irish architect, best known for building the General Post Office (GPO) on O'Connell Street, Dublin.

[3] Two early projects were the completion of Rokeby Hall and Ballymakenny Church, Co. Louth, to the designs of Thomas Cooley in whose office he first trained.

The great Pillar and Post Office were designed to harmonise with each other in the street adding grandeur and elegance to the boulevard.

His work is interesting from an architectural point of view, in that it spans both the Neoclassical and Gothic Revival styles.

This gateway had to be moved to the Royal Hospital Kilmainham after the arrival of the railway in 1847 increased traffic congestion.

The original plans for the Pillar were submitted to the organising committee by William Wilkins, a London architect, and accepted by them in 1808.

[15] He was responsible for the design of Charleville Forest Castle in Tullamore, County Offaly,[4] considered one of the finest of its type in the country.

[citation needed] He lived for many years in his house at 64 Eccles Street, where he kept a large collection of curiosities.