Ardgillan Castle, Country estate with castle in Balbriggan, Ireland

Ardgillan Castle is a two-storey country house over a basement, built in 1738 for Reverend Robert Taylor and given castellated rooflines. Its grey stone walls, white-framed small-pane windows and a chimney stack with several capped flues face a broad green hedge. The basement extends under the south lawns, and the house overlooks Barnageera Beach and the Irish Sea.

The core of the estate, originally called Prospect House, was built in 1738 for the Taylor family. Over generations it was expanded with additional sections that shaped its current form.

Upstairs, the former bedrooms hold a permanent exhibition of the Down Survey colour maps and text, produced in the 1650s under William Petty, not Thomas Taylor. The Taylor family, who built Ardgillan in 1738, lived here until 1962. The ground floor rooms and kitchens can be seen on guided tours.

Guided tours cover the ground-floor rooms and kitchens; the former bedrooms upstairs hold exhibitions. Tea rooms sit off the main reception area. The Lady's Stairs footbridge over the Dublin–Belfast railway is reached by concrete steps a short walk from car park one, and the line is also visible from the hill near the playground.

The Alcove Wall in the garden was built during the 1840s famine as a relief work program created by the Taylor family. The structure provided employment and was designed to shelter fruit trees during harsh seasons.