For a landmark property, Castleton hides its biggest secret – a massive back garden – well. Nor is the house itself fully on view; the parts visible of the period house on the south side of Sandymount Green include a two-storey gable wall with pointed arch sash windows and a roof decorated with castellated battlements.

It’s all classic 19th century gothic. The modest entrance is an arched doorway in its red-painted wall, so while it is clear from a distance that this is a picturesque property, there’s not much indication from outside that Castleton extends to 353sqm (3,800sqft), with four or five bedrooms, has several reception rooms and grounds that cover more than a third of an acre of mature gardens.

Step through that black-painted wrought iron door in the exterior wall and you’re in an atmospheric enclosed courtyard created when a single-storey wing was added in the 1980s to make space for an additional bedroom and an informal living room. It’s a sympathetic addition in that you could easily believe it came from original converted stables or outbuildings. The dramatically large arched front door is to your left, set in a crenulated porch – the gothic touches are everywhere in this house including a secret winding staircase up to the roof.

Appealing rooms

The most attractive room – in a house with an abundance of appealing rooms – is the beautifully proportioned formal drawing room. It is upstairs with windows on three sides including a deep bay with a window seat and views out on to Sandymount Green. Striking original features in this room include a fine fireplace and delicate ceiling plasterwork. The main bedroom suite is nearby and it incorporates a dressing room and a stunning relatively recent marble-clad bathroom en suite which is so large it must have once been at least one bedroom. A balcony overlooks the rear garden. There’s a further double bedroom up here and a tiny single room.

Down at hall level there’s a spacious eat-in kitchen fitted with contemporary units, a formal dining room, a library and the usual assortment of service rooms including a boot room and a utility room. There is access to the back garden from several rooms. Castleton is for sale through Sherry FitzGerald for €2.75 million.

Massive renovation

The pink castellated house next door is currently undergoing a massive renovation – called Castleville, it is not as big as its neighbour, has a considerably smaller garden and it sold in 2015 for €1.675 m. While buyers of Castleton will almost certainly do some decorative work – not everyone will love the paint treatments and the trompe l’oeil on the landing – they could easily move in and enjoy this landmark property.

Castleton and Castleville are semi-detached and there is a small lushly planted garden to the front belonging to Castleton between the two – though it’s difficult to see it being much used. Further along that exterior wall is a set of gates giving vehicular access – so private off-street parking for several cars is not going to be a problem.