Portumna Castle is located close to the shore of Lough Derg near where the River Shannon enters the lake.

Its builder was Richard Burke, 4th Earl of Clanricarde, Lord President of Connaught, of the de Burgo family of Norman descent.

Portumna castle was built in the Renaissance style already prevalent in Italy and France for over a century, but not commonly found in Ireland or England at that time.

The castle is symmetrical in shape and consists of three stories over a basement with square corner projecting towers.

A central corridor, 3m wide, runs longitudinally from top to bottom, supported by stone walls, which contain numerous recesses and fireplaces.