Liberty Hall, Dublin's tallest building, stands in the background. In the foreground is Dublin's Ha'penny Bridge.

Liberty Hall, in Dublin, Ireland is the headquarters of the Services, Industrial, Professional, and Technical Union (SIPTU), was formerly the tallest building in Ireland (the tallest is the County Hall in Cork city) and is currently the tallest building in Dublin. It is more historically significant in its earlier form, as the headquarters of the Irish Transport and General Workers Union early in the 20th century, and as that of the Irish Citizen Army (ICA).

Standing on Bereford Place, near the Custom House, the original Liberty Hall used to be a hotel before becoming James Connolly's personal fortress with Dublin. From 1913 through 1916 it was kept under constant armed guard by the ICA, and hence, though it was Dublin Castle's primary adversary, it was probably the safest place in Dublin for rebel activity. Following the outbreak of World War I a banner reading "We serve neither King nor Kaiser but Ireland" was hung on its front wall, and within was printed the newspaper The Irish Worker. Because the building was so heavily guarded, The Irish Worker was the only subversive paper in the city that wasn't shut down under the Defense of the Realm Act .

Prior to the Easter Rising of 1916, Liberty Hall acted as a munitions factory, wherein bombs and bayonets were made for the impending rebellion. It was on the street in front of the building that the leaders of the rising assembled before their march to the General Post Office on Easter Monday. They left the building vacant throughout Easter Week, a fact unknown to the British authorities, who chose the building as the first to be shelled with artillery. It was destroyed in due course, and eventually rebuilt in its current form.