The GPO is marking 200 years since it first opened for business.
A new stamp has been issued to mark the occasion.
The historical building began operations back in January 1818 - and is indelibly associated with the 1916 Rising.
But the building, designed by Francis Johnston, has seen much more than the events of Easter Week.
The foundation stone was laid by Lord Whitworth on August 12th 1814.
As the century progressed, the GPO presided over an organisation that - through mail, financial services, telegraphs and telephones - touched the lives of countless people every day.
The GPO was the focal point of the Easter Sunday commemoration ceremony and parade on O'Connell Street in 2016 | Image: RollingNews.ie
It became the centre of communications in Ireland - and, for some, an unacceptable manifestation of British influence in the country.
Its occupation on Easter Monday 1916 was seen to have a practical and symbolic purpose.
Reconstruction and extension of the building after it was destroyed was undertaken by an OPW team led by TJ Byrne.
He introduced the GPO Arcade, studios for Radio Éireann on the Henry Street wing and the Central Telegraph Office in the Prince’s Street block.
The GPO continues to operate in its original purpose: as the headquarters of the Irish Post Office.