Cahir Castle sits on a rocky island in the River Suir, in the middle of the town. It is one of the largest and most complete medieval castles in Ireland. The reason it is so complete is that the people holding it kept giving it up.
From 1142 to the Butlers
There was a fortification on the island from 1142, founded by Conor O'Brien. In 1375 Cahir was granted to James Butler, newly created Earl of Ormond, for his loyalty to Edward III, and it stayed with the Butler family from then on. The OPW dates the main structure you walk around to the thirteenth century, and much of the rest of it was built or rebuilt by the Butlers across the fifteenth and sixteenth centuries. The short version is that the site is older than the building and the building is older than almost anything comparable still standing in Ireland.
The siege of 1599
In 1599 the Earl of Essex brought an army and artillery against Cahir. The siege lasted three days, the east wall was breached, and the castle fell with the loss of around eighty defenders. It was then held for a year under Sir Charles Blount. It was one of the few real sieges of the Nine Years War and, at the time, a considerable embarrassment for the Butlers.
Why it is still standing
In 1650 Cromwell arrived during his conquest of Ireland. The garrison accepted terms and surrendered without a shot being fired, and Cromwell left the castle intact. Castles that resisted him were slighted. Cahir did not resist, so Cahir is still here, and that single decision is why visitors can walk through a genuinely medieval building rather than a ruin.
The family held it until 1961, when the last Lord Cahir died and the castle passed to the Irish state. The Butler association with Cahir had run for close to six hundred years by then. They had stopped living in the castle long before that, having built Cahir House on the Square in the 1770s, which is now the town's hotel.
What there is to see
The castle keeps its curtain walls, towers, a keep and a working portcullis, and the layout is legible in a way that ruins rarely are. You can climb, walk the walls and get out onto the river side of the island. The Office of Public Works runs the site with guided tours and an audio visual presentation. Take the tour. The building makes far more sense with someone explaining what each part was for.
Allow more time than the size suggests. Stairs, spiral steps and uneven stone throughout, so think about that if anyone in the group is unsteady.
Planning a visit
Opening times, admission and tour arrangements are all set by the OPW and change with the season, so check the official OPW page for Cahir Castle rather than relying on any figure printed elsewhere. Booking ahead is sensible in summer.
The castle is in the middle of the town, so park once and walk. Getting to Cahir covers the approach from the M8 and where to leave the car.
The walk to the Swiss Cottage
The best thing to do after the castle is the riverside walk south along the Suir to the Swiss Cottage, an ornamental cottage orne built for the same family. It takes about half an hour each way on a good path and it is the walk that makes a visit to Cahir into a day rather than a stop. Walking in Cahir covers the rest of the routes.
On screen
The castle has been used as a filming location often enough that it may look familiar before you arrive. Movies filmed in Cahir covers what was shot here.
Nearby
Things to do in Cahir covers the rest of the town, and things to see covers the wider area, including the Rock of Cashel and the Vee.