Rathfarnham Castle began life as an Elizabethan fortified house. The Archbishop Chancellor, Adam Loftus commissioned the building in the 1580s and the design was radically modern at the time. The angled bastion towers located at each corner of the building were equipped with musket loops which allowed a garrison of soldiers to defend all approaches to the castle. Some of these musket loops are still visible today.

Extensive remodelling and redecoration of Rathfarnham Castle took place in the eighteenth century under a series of owners, and the castle was transformed into a fashionable country villa. The design of several rooms has been attributed to the renowned architects Sir William Chambers and James Athenian Stuart including the elegant Ballroom, the ornate Four Seasons Room and the Gilt Room.

Rathfarnham Castle was acquired by the Society of Jesus in the early 20th century and was used as a retreat house and residence until the 1980s. Following the departure of the Society of Jesus, this 16th century fortified house was declared a National Monument and purchased by the Irish State. Rathfarnham Castle is managed by The Office of Public Works and open to the public. A programme of restoration work began in the 1990s and is ongoing. Rathfarnham Castle hosts exhibitions of contemporary art and a varied programme of cultural events throughout the year.

Rathfarnham Castle is situated in the village of Rathfarnham, South Dublin. Buses servicing the area from Dublin City are bus 16 or 15b.