The OPW (Office of Public Works) manages a lot of heritage sites across Ireland. While entry to many of these sites isn’t expensive, they also offer free entry on the first Wednesday of the month to some locations.
While not every property offers the free entry there is a very good selection to choose from including:
- Donegal castle (Donegal town)
- Charles Fort (Kinsale)
- Athenry Castle
- Trim Castle
Bear in mind that not all properties are open all year round and some have restrictions on visitors.
Full details here.