This fortress was one of the long chain of the Pale castles which defended the metropolis, but having been inhabited until the beginning of the nineteenth century it is in a much better state of preservation than most of these old buildings.

It is situated about three miles south of Dublin on a rise of ground above the Dundrum River, a tributary of the Dodder, at the junction of the Ballinteer and Enniskerry roads.

It is probable that the castle was built on the site of a more ancient stronghold, as Dundrum signifies “the fort on the ridge.”

The principal ruin of the present castle is a keep which is battlemented in a slightly projecting form on the south-east, while the south-west wall rises in rather a high gable. The building is oblong in shape, and the entrance, which is on the south side, is evidently of more modern construction. A gate now gives egress to the interior, which is occupied by a flower bed.

Two large windows on the ground floor also point to later alterations, especially as they occur simultaneously with the remains of earlier openings.

The stairs are likely to have been situated in the south-west side. There are numerous small chambers and passages in the thickness of the walls.

Of the three fireplaces in the north-west wall that on the ground floor is the largest, measuring 9 feet long by 5 feet high, and as the flagstones of the hearth are covered by some inches of gravel its height was once greater. At the back of the fireplace and slightly to one side is an aperture about two feet square, which is framed in cut stone, and was probably used as an oven.

On the south-west end of the keep are the ruins of a smaller building several storeys high, which is connected with the main building by a square topped doorway. The dividing wall is nearly 6 feet in thickness.

Both buildings are largely covered with plaster, and on the south-east the keep has been partly rough cast.

The situation of a third building can be seen adjoining the tower on the north-east side, where the pitch of its roof may be traced about three-fourths of the way up, but very little of the walls remain.

The castle is partly covered with ivy.

The fortress seems to have been built soon after the Norman invasion, and as the lands of Dundrum were held by Hugh de Clahull, it was probably erected for their defence. It subsequently passed to the Fitzwilliams of Merrion, from whom it descended to the Earls of Pembroke, and it forms at present part of the Pembroke estate.

Robert le Bagod, ancestor of the Fitzwilliams, had license to convey the manor of Dundrum to his son William, and in 1332 Thomas Fitzwilliam was found seized of the lands round.

From this time on it is likely the fortress was occupied by cadets of the Fitzwilliam family.

In 1542 Sir Thomas Fitzwilliam was in possession of the manor, and in 1616 his grandson Thomas, afterwards first Viscount Fitzwilliam, recovered the lands of Dundrum and Ballinteer, with the castle and water mill.

His brother William, who had married Archbishop Ussher’s widow, lived at Dundrum Castle about this time.

The building was slated and in good repair during the Commonwealth. It is stated to have had three hearths and a barn, with a garden.

It was tenanted by a Mr. Isaac Dobson during the reign of Charles II. He was a Nonconformist, and probably a trader in Dublin. When James II. came to the throne he left the country, and was attainted by Parliament in 1689.

His son, who was a bookseller, succeeded him at the castle. He greatly improved the grounds, and when he died in 1720 he left the use of the castle to his wife for her life, after which it went to his sons.

The last Dobson who lived in it died in 1762, and when Mr. Cooper visited it in 1780 it was most likely inhabited by a farmer, who was then cutting down the grove of ash which grew between it and the river.

He speaks of the inhabited part as a modern addition to which older remains were adjoining. He states that the principal entrance was from the courtyard by stone steps.

It soon afterwards fell into ruin, and at the beginning of the nineteenth century the present modern dwelling-house was erected. This was at first inhabited by the Walsh family, and later Dr. Reichel, Bishop of Meath, lived in it. Miss Hume is the present occupier.