Mountjoy Square (Irish: Cearnóg Mhuinseo) is a Georgian garden square in Dublin, Ireland, on the Northside of the city just under a kilometre from the River Liffey. One of five Georgian squares in Dublin, it was planned and developed in the late 18th century by Luke Gardiner, 1st Viscount Mountjoy. It is surrounded on all sides by terraced, red-brick Georgian houses. Construction of the houses began piecemeal in 1792 and the final property was completed in 1818.