King John's Castle

The castle was built from about 1200 on the orders of King John on King's Island, where the Shannon narrows, on a site that had been a Viking settlement - excavation under the courtyard exposed the post-holes and floors of pre-Norman houses, and those are displayed in situ beneath the visitor centre, which is the most interesting thing on the site. The castle is a keepless design, relying on a curtain wall with round towers and a twin-towered gatehouse. It was besieged repeatedly in the seventeenth century, most heavily in 1642 and during the Williamite wars, and a siege mine and countermine tunnel dug under the walls in 1642 were found and are shown. The visitor centre opened in its current form in 2013 with heavy use of screens and reconstructions, which divides opinion - some find it well done, others feel it crowds out the fabric.

What you actually see

• The Viking houses - pre-Norman floors excavated under the courtyard.
• The siege tunnels - the 1642 mine and countermine beneath the walls.
• The curtain and towers - a keepless Norman design on the Shannon.
• The visitor centre - screens, reconstructions and interpretation from 2013.

When to go

Any season; largely indoors, with courtyard and wall walks outside. Reduced hours in winter. Two to three hours for the full circuit.

Honest expectations

The interpretation is screen-heavy and reconstruction-led, which some visitors find intrusive. Ticketed, at the higher end for an Irish castle. Wall walks close in high wind.

Nearby

Saint Mary's Cathedral is on the same island; the Hunt Museum is across the river.