Dangan Castle, Castle ruin in Summerhill, County Meath, Ireland

Dangan Castle is a ruined stately home by Dangan Church on the Trim Road outside Summerhill, County Meath. The surviving main block is a pale grey stone building with two rows of rectangular openings, six above and five below around a central doorway, a low-pitched roof and a small square crenellated tower at its centre; a roofless wing extends to the left.

Richard Colley built the modern house in the early 1700s after inheriting the estate from Gerald Wesley on condition he change his surname to Wesley. His grandson Arthur Wellesley, the future Duke of Wellington, spent most of his childhood here. In 1809 a fire destroyed much of the building, and by 1841 only the outer walls remained.

The Wesley family held the estate from the 12th-century conquests of Henry II until Richard Wellesley sold it in 1781 to Thomas Burrowes of the East India Company. Richard Colley took the Wesley name as a condition of inheriting from the childless Gerald Wesley. His son Garret Wesley, 1st Earl of Mornington, was father of Arthur Wellesley, the future Duke of Wellington, who spent most of his childhood here.

The site sits roughly two kilometers from Summerhill village and is easiest to reach by car. Visitors should expect that access to the grounds may be limited and the ruins are weathered, so sturdy footwear helps when exploring.

The estate once featured a sizable lake that was created when gardens were being developed on the property. This water feature was a major part of the landscape design but has now disappeared from the site.