The OPW (Office of Public Works) cares for, maintains, and operates 780 important heritage sites across the Republic of Ireland. The goal of the organization is to preserve and protect structures in its care while providing safe public access and information to visitors.

The OPW Heritage Card is a single-charge card that grants unlimited access to OPW managed historic sites and visitor attractions for one year, including guided tours. Cards are available for individual adults, seniors, and children, as well as a family card that includes 2 adults and 5 children over 12. Children under 12 can access OPW Heritage sites at no cost.

There is no need to purchase an OPW Heritage Card prior to arriving in Ireland, just buy it at the first fee-paying OPW site you visit.

Ireland's Most Visited Heritage Sites in 2024

Each year Ireland's Office of Public Works share the previous year's data about visitor numbers and the most visited OPW sites. in 2024, recorded visitors to Ireland's heritage sites exceeded 13.8 million

The two most-visited heritage sites carry no fee, and both are located in Dublin.

St. Stephen's Green, a wonderful green space in the heart of the city centre, saw nearly 4.5 million visitors in 2024. This isn't surprising as the park is a wonderful place for a walk and the playground is quite nice. It is also a pretty ‘shortcut' as you walk point to point in Dublin.

The Phoenix Park visitor centre recorded approximately 2 million visitors. Again, no surprise as this massive park, less than 5km from Dublin city centre and easy to reach via bus or Luas, is a popular spot for recreation as well as home to Dublin Zoo.

Most Popular Heritage Sites in Ireland (Ticketed Admission)

Dublin Castle, Dublin – 534,014 visitors

Dublin Castle leapt into first place this year, unseating 2023's most popular castle (which is now at #2).

Located in the heart of Dublin, Dublin Castle was built in the early 13th century and served as the center of power for the English (and later British) government.
Prebooking is recommended for the guided tour as space can be limited. Bookings can be made up to 15 days in advance.

Kilkenny Castle & Parklands, County Kilkenny – 429,546 visitors

The central point of Kilkenny City, Kilkenny Castle has the feel of a royal palace, making it a very grand place to visit. It's important to note that the parklands are free to visit.
Prebooking is not required.

Rock of Cashel, County Tipperary – 365,505 visitors

The magnificent Rock of Cashel was originally built as a fortress in the late 4th or 5th century as the seat of the kingship of Munster and the inauguration place of its kings. In the 7th century St. Patrick baptized a King of Munster here and in 1101 the reigning King gave the fortress to the Church. This impressive structure was given into State care as a national monument in 1869.
Prebooking is not required. I do highly recommend joining one of the guided tours as the hitory of the site is fascinating.
Cormac's Chapel, which contains the only surviving Romanesque frescoes in Ireland, can only be accessed by guided tour. Tickets for this tour ‘extension' are only available on site and space is limited.

Kilmainham Gaol, Dublin – 243,078 visitors

Opening in 1796 as the new County Gaol for Dublin, thousands of men, women, and children were held here for everything from minor offences to organized rebellion. The stories you will hear are powerful in both sadness and strength.
Prebooking is necessary as tickets sell out quickly. Booking opens 28 days in advance of your visit at midnight Irish time. Here's how to book your tickets.

Dún Aonghasa, Inis Mór, Aran Islands, County Galway – 146,089 visitors

Dún Aonghasa is the largest prehistoric stone fort on the Aran Islands. Consisting of 3 massive drystone defense walls further surrounded by a dense band of jagged stones and perched on the cliff edge, Dún Aonghasa is an imposing structure built for defense.
Prebooking is not required.
Visitors should note that there is a 1km walk from the visitors centre to the site that includes rough, natural rock. There is no fencing or barriers at the cliff edge.

Ross Castle, County Kerry – 143,016 visitors

Ross Castle, located in Killarney National Park, is a top spot for the jaunting cars as well being the boat launch location for the Lakes of Killarney and Gap of Dunloe.
This 15th century tower house was one of the last strongholds in the region to surrender to Oliver Cromwell in 1652.
Guided tours are available March thru October, but you can visit the grounds year-round at no charge. Prebooking is not necessary.

Brú na Bóinne (including Newgrange and Knowth), County Meath – 133,991visitors

I have no doubt that the only reason Brú na Bóinne is number 7 on this list is because tour numbers are limited.

This UNESCO World Heritage site consists of 3 prehistoric passage tombs – Knowth, Newgrange, and Dowth – built circa 3200BC and contain the largest collection of megalithic art in Western Europe.
Access to the visitors centre is available to anyone with no booking required.
Access to the tombs of Newgrange and Knowth is by guided tour only and prebooking is essential.
Booking opens 30 days in advance of your visit at midnight Irish time. Here's how to book.

Clonmacnoise, County Offaly – 118,337 visitors

Located at one of the most important crossroads of ancient Ireland, the monastic village of Clonmacnoise has 3 high crosses, two round towers, and nine churches. This site is easy to visit if you are traveling from Dublin to Galway (or vice versa). This is a wonderful spot to explore, especially if you don't visit Glendalough in County Wicklow (which, surprisingly is not among the top 10 visited sites, likely because the grounds are free and numbers reflect paid entry to the visitors centre).
Prebooking is not necessary.

Trim Castle, County Meath – 113,372 visitors

Trim is the largest Norman castle in Ireland, taking 30 years to build. Built in a cruciform shape with 20 sides and surrounded by a ditch, curtain wall, and water filled moat, it was all nearly impenetrable. The grounds of Trim Castle and the charming river walk are free to visit. Visits in the castle are by guided tour only.
Prebooking is not available; daily tours are first come first served and do fill, so plan a bit of time here in case you need to wait. Tour times may change daily.

Charles Fort, County Cork – 104,723 visitors

This star-shaped military fortress guarding the mouth of Kinsale Harbour was constructed in the late 17the century. And while it withstood a 13-day siege during the Williamite Wars, the design and location of the fort ultimately proved to be flawed.
Prebooking is not necessary.

My Favorite Heritage Sites in Ireland

My favorite heritage sites in Ireland didn't make the ‘Top 10' list, but that doesn't mean they aren't spectacular, only a bit off the beaten path.

Cahir Castle, County Tipperary – 87,343

Ireland's second-largest Norman castle is just 30 minutes south of the Rock of Cashel but receives only 20% of the visitor numbers. This is my favorite castle in Ireland due to the small number of visitors and the fact that you can explore nearly every part of the castle and grounds. The lovely island behind the castle is a perfect spot for a picnic, and a short woodland stroll takes you to another OPW site, the Swiss Cottage (which only received 18,295 visitors in 2024).
Prebooking is not necessary. and I highly recommend the included guided tour.

Rock of Dunamase, County Laois – 47,123

If you are traveling between Limerick and Dublin or Dublin and Kilkenny, this is my #1 spot to visit, the ruins of a massive fortress sprawling atop a rocky limestone outcrop. If you're the type to believe in ‘thin places' you'll want to come here as the power of the location can be felt as you catch sight of the ruins. The high situation and views of the surrounding countryside made this a strategic spot for a stronghold, though it appears the castle was abandoned in the 1330s.
This is a free, open site with no visitor centre.

Carrowmore Megalithic Cemetery, County Sligo – 30,594 visitors

While the tombs at Carrowmore in Sligo may not have the recognition of Newgrange this location is host to one of the most densely populated complexes of tombs in Ireland, as well as some of the oldest, dating back to 3700BC (older than Newgrange). Within the OPW site are at least 30 passage tombs in various states of survival, with at least 25 more known to be destroyed since 1800. Tomb 51, the largest on site, has been excavated, revealing a roofed central chamber and megalithic art.
Prebooking is not necessary.
Note: the site has been closed for most of 2025 for visitor centre updates and is due to reopen in August.

Kells Priory, County Kilkenny – 30,349

Locally known as the ‘Seven Castles', the Augustinian Priory at Kells encloses nearly 3 acres. With its seven tower houses spaced along the walls it has the appearance of an enclosed village. The priory has an intriguing past that includes being burned 3 times and, in 1324, it played host to the first known witch trial in Europe. Take your time exploring this site, including a lovely walk by the river to the old mill.
This is an open site, free to visit with no visitor centre. Guides may be available from June – August.

Scattery Island, County Clare – 4,398

Located in the Shannon Estuary, Scattery Island can only be reached by boat, a very calm 30-minute cruise from Kilrush Marina. The monastic site dates to the 5th century and features multiple churches, a cathedral, and a round tower – with its door at ground level. The island is also home to a Napoleonic artillery battery and a working lighthouse built in 1872. Very few people take the time to add Scattery Island to their Ireland itinerary, but its location is a perfect fit if you are traveling the Wild Atlantic Way between the Cliffs of Moher and Killarney.
Though it is free to visit the site – and you can even get a guided tour! – you do need to make a reservation for the ferry with Scattery Island Tours.

Traveling in Ireland podcast episode 288

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