Lea Castle, Ruined medieval castle near Portarlington, County Laois, Ireland

Lea Castle is a ruined medieval castle on the south bank of the River Barrow near Portarlington, County Laois. Its remains, mostly 13th-century, consist of a four-storey donjon with a circular tower at each corner and a twin-towered gatehouse in the outer ward to the east. A curtain wall partly survives around the inner enclosure.

A timber castle was built in the late 12th or early 13th century and later replaced in stone. The FitzGeralds, Earls of Kildare from 1316, held Richard de Burgh, 2nd Earl of Ulster, prisoner here for several months in 1294–5 until Parliament secured his release. The castle was besieged in 1307, captured by the O'Dempseys in February 1330 and retaken by Maurice FitzGerald, 1st Earl of Desmond. After unrest following the death of justiciar Ralph de Ufford in 1346, it was destroyed by the O'More, O'Connor Faly and O'Dempsey families, captured again in 1452, and in 1650 the donjon was partly blown up and left a ruin.

The castle shows how Anglo-Norman settlers built their strongholds by combining timber and stone methods. The way the walls curve along the river reflects how medieval builders used water as a natural defense.

The ruins stand on the south bank of the River Barrow near Portarlington, County Laois. The surviving donjon and twin-towered gatehouse are reached from the riverside; the north corner tower is the tallest part left standing. The site is on private land, so ask the owners before walking the banks.

Richard de Burgh, a powerful Anglo-Norman nobleman, was held prisoner here for months by the Fitzgerald clan in the 1290s. His release came only after Parliament stepped in to negotiate, showing how central this fortress was to regional power struggles.