Kilmainham (Irish: Cill Mhaighneann, meaning "St Maighneann's church") is a suburb of Dublin south of the River Liffey and west of the city centre, in the Dublin 8 postal district.
In the Viking era, the monastery was home to the first Norse base (longphort) in Ireland.
In the 12th century the lands on the banks of the Liffey first belonged to the Knights Templar. Strongbow erected for them a castle about a mile distant from the Danish wall of old Dublin; and Hugh Tyrrel, first Baron Castleknock, granted them part of the lands which now form Phoenix Park. Here the Templars flourished, for nearly a century and a half, until the process for their suppression was instituted under Edward II, in 1308. Thirty members of the order were imprisoned and examined in Dublin and the order was condemned and suppressed. Their lands and privileges were given to the priory of the Knights of St. John of Jerusalem, who remained in possession until the dissolution of the monasteries in the 16th century.
Until the time of Queen Elizabeth, when Dublin Castle became the centre of English power, the Lord Lieutenants often held court at the manor of Kilmainham. In 1559, the earl of Sussex, on being again appointed Lord Lieutenant, found that the building at Kilmainham had been damaged by a storm, and had to hold court at the palace of St. Sepulchre. The following year Elizabeth ordered that Dublin Castle be upgraded to enable the Lord Lieutenant to reside there, and Kilmainham fell out of favour.