Ballinafad Castle, Elizabethan blockhouse in County Sligo, Ireland

Ballinafad Castle, also called the Castle of the Curlews, is a ruined Elizabethan blockhouse on the east side of the N4 overlooking Lough Arrow in south County Sligo. It stood three storeys high, with square rooms in all four corner towers except the north tower, which was round and held a wooden spiral stair up to the roof. The entrance was in the north-west wall at first-floor level.

An English military officer built this stronghold in the 1590s during a major conflict between English forces and Irish rebels. The founder remained in residence for several decades until the fortress was eventually abandoned.

The castle's other name, Castle of the Curlews, comes from the Curlew Mountains, the range whose road it was built to guard. The village name Ballinafad is Irish Béal an Átha Fada, "mouth of the long ford". The ruin is a national monument of Ireland.

The ruins sit on a hillside and can be visited free of charge through a small metal gate at the base of the slope. A simple parking area below provides access to a footpath leading up to the site.

The north tower still shows remains of a wooden spiral staircase that once connected all three floors of the structure. This type of interior feature was uncommon in fortifications of that era and suggests the original building maintained higher comfort standards.