Rising above the plains of County Meath between Navan and Dunshaughlin, the Hill of Tara makes a solid case for being the single most important historical site in the country. Long before the Celts or Iron Age chieftains, the Neolithic people of the Stone Age considered it a sacred place – the home of the gods and a gateway to the world beyond. Beneath the grassy slopes are passage tombs dating from the same period as those at nearby Brú na Bóinne, although they have yet to be properly excavated.  

The site remained a centre of spiritual importance right through to the Iron Age, when it became the seat of the High King and, therefore, the capital of Ireland, the island’s centre of political and religious power. It was here that St Patrick came to challenge the ancient beliefs with the new religion of Christianity. Nearly 1,500 years later, Daniel O’Connell spoke to over one million people here in 1843 at one of his monster rallies – the hill was explicitly chosen because of its deep political and spiritual significance.  

The hill is open to visitors all year, but the excellent visitor centre (in a deconsecrated church with stained glass windows by artist Evie Hone) is only open from May to September and features an instructive, 20-minute audiovisual introduction to the hill. Guided tours are also available at these times; otherwise, you explore the site at your leisure.  

Highlights include the Mound of the Hostages, a 5000-year-old passage tomb and the Ráith na Rí, or Fort of the Kings – the largest and most important enclosure at Tara. This vast, circular earthwork, marked by a double bank and a ditch, measures approximately 300m in diameter. Within its earthen walls are some of the hill’s other key sites, including the Lia Fáil, or Stone of Destiny, where the high kings were crowned (and which was said to roar when the rightful king was found); and Teach Cormaic (Cormac’s House), associated with the legendary King Cormac mac Airt.

Near Oldcastle in County Meath, Loughcrew Cairns form one of Ireland’s most remarkable archaeological landscapes – a complex of Neolithic passage tombs dating back over 5,000 years. Part of a chain of sacred hills that once linked with Tara and Brú na Bóinne, this site offers a window into the minds and mysteries of Ireland’s earliest settlers. 

At its heart is Cairn T, whose chamber walls are etched with exquisite spiral and lozenge carvings - some of the finest examples of Neolithic art anywhere in Europe. The alignment of the passage to the rising sun at the equinox reveals the builders’ deep understanding of astronomy and ritual. Centuries later, the discovery of Iron Age bone combs and slips decorated in La Tène art in nearby Cairn H shows the site’s enduring spiritual and cultural importance. 

Open from early June to early September, Loughcrew is free to visit, with guided tours available. 

Rathgall, or An Ráth Gheal in Irish (The Bright Fort), was home to Celtic royalty, specifically to Crundmáel Bolg Luatha mac Áedo (who died in 628 AD), a King of the Uí Ceinnselaig family dynasty.  

But evidence suggests that the fort, which is just outside Tullow, dates back to the late Bronze Age (800 BC) and was used continuously through to the early Middle Ages. An 8th-century outer wall and medieval inner walls ring the fort you see today, which sits at the edge of a ridge with panoramic views of the surrounding countryside. 

Photo credit: @carlow_tourism

Over the years, the site has proven to be a rich resource of relics, from Bronze Age tools to medieval coins and pottery. An iron-smelting furnace uncovered there also indicates Rathgall’s use in the Iron Age.  

The fort is free to visit at all times, but as it is an unguided site, you’ll need to exercise a level of care and attention when exploring. 

An extinct volcano rising from the flat, low plains of the Bog of Allen is just the start of what makes Croghan Hill a worthwhile climb. The mound at the top of the hill is believed to be a Bronze Age burial site. Later visitors, including St Patrick and St Brigid, solidified the hill’s importance as a Christian site.  

An engraved pillar at the top of the hill, created by artist Ciaran Byrne, features four panels that showcase the hill’s central role in history and myth. There’s a panel showing the ancient volcano (350 million years ago), another showing St Brigid receiving her veil, and another illustrating St Patrick’s horse kicking a rock that miraculously sprung a well (that well is still there, just outside Croghan village).  

The fourth panel refers to the 2003 find of Old Croghan Man in the bog at the foot of the hill, one of Ireland’s most significant archaeological discoveries. This remarkably well-preserved Iron Age body is thought to have been a chieftain of some importance who was ritually killed as part of a macabre ceremony to appease the gods; his remains are stored in the Kingship & Sacrifice exhibit at the National Museum of Ireland, Kildare Street in Dublin. The mystery of what happened to him is the subject of the podcast, The Discovery Series: The Bog Bodies.  

In the Iron Age, toghers were wooden trackways that were essential for transportation, consisting of wooden boards laid across the bogland. The Corlea Trackway, which sank into a bog and was preserved for approximately 2,000 years, is one of the largest of its kind uncovered in Europe. The discovery of the trackway is just part of the ongoing conservation work of the local bog, which allows visitors to experience what it was like for people of the Iron Age to move around. 

The visitor centre is open from March to early November. Inside is an 18-metre stretch of the ancient wooden structure, on permanent display in a specially designed hall to preserve it.  

Spanning 9,000 years of Irish history, the Irish National Heritage Park at Ferrycarrig, just outside Wexford town, offers visitors an immersive, open-air experience of Ireland’s ancestral past amid 40 acres of lush woodland, marsh and shoreline. The park is divided into epochs, and you can learn about different historical periods by walking through heritage trails that span the establishment of the first settlements on the island to the arrival of the Normans in the 12th century.  

In total, there are 16 reconstructed sites, including a dolmen, a Bronze Age cooking site (known as a fulacht fiadh), and a crannog (an artificial island). The park also offers a range of specific experiences, including a day in the life of a Viking, talks on Birds of Prey with the park’s Master Falconer and more. 

Rathcroghan was the ancient capital of Connaught, ruled over by Queen Maeve. It is part of the archaeological landscape of Cruachan Aí, the oldest and largest unexcavated royal site in Ireland. It’s home to 240 identified archaeological sites, which you can learn all about at the Rathcroghan Visitor Centre and explore as part of a range of guided tours.  

Here you’ll find ringforts, standing stones, prehistoric burial mounds from the Bronze and Iron Ages, and even a genuine Iron Age ritual sanctuary. Rathcroghan is also believed to be the birthplace of the Samhain rituals that marked the Celtic New Year. 

Nearby lies Oweynagat, the fabled “Cave of the Cats”, said to be a gateway to the Otherworld. According to ancient belief, its doorway opened at Samhain, when the boundary between the living and the dead grew thin. Centuries later, wary Christian scribes renamed it the “Gate to Hell” – a title that only adds to its dark allure. 

Mighty Queen Maeve was always going to have an impressive resting place, and there’s none that quite match the top of Knocknarea Mountain, Sligo’s most distinctive peak. You ascend the 1,078 feet of it via Queen Maeve’s Trail, a 2.3km-long path to the top of the mountain via steps, paths and a wooden bog bridge at the end. Along the way, info posts with QR codes tell the story of the mountain’s mythological connections – the good news is that the posts are strategically located at the end of the steepest bits of the climb, so you can catch your breath while you learn.  

Queen Maeve’s Cairn is an enormous heap of small stones, formed in the shape of an oval, atop the mountain. It was built by the Neolithic people around 3000 BC, and stories of Maeve’s burial may have actually been inspired by the tales of King Eoghan Bel of Connacht, who may be the tomb’s real occupant. Either way, the monument makes for an iconic hiking destination – although visitors are advised not to disturb the stones and to maintain a respectful distance to ensure the cairn’s preservation. While at the top, consider this: the total weight of the cairn’s stones is around 40,000 tonnes – and each of those was carried up by hand along the same path you just ascended.  

Built in the late Bronze Age, circa 950 BC, Mooghaun Bronze Age Hillfort is one of the largest of its kind in Ireland, offering impressive views of both the nearby River Fergus and the Shannon estuary.  

It is believed that the inner part of the hillfort, beyond the ramparts, was a sacred space where ceremonies and special gatherings were held. The importance of this area is further suggested by the Mooghaun North Hoard, the largest hoard of prehistoric gold in Western Europe, discovered in the vicinity in 1854. What remains of that collection now rests in the National Museum of Ireland and the British Museum. Still, visitors to County Clare can take a self-guided trip to see Mooghaun’s cashels for themselves and take in the site’s surroundings.  

The ancient world is alive and well, just a stone’s throw from Shannon Airport at the Living Past Experience at Craggaunowen in Kilmurry. Watch artisans craft clothes, tools and tales, or explore a reconstructed fulacht fiadh. Step into a crannog, the Iron Age wooden dwelling built over bodies of water, or walk through Craggaunowen’s ringfort, a faithful reproduction of a farmer's house dated to the 4th or 5th century, complete with a souterrain, an underground shelter for when the ringfort came under attack.  

Pride of place goes to a long leather vessel dubbed the ‘Brendan Boat.’ In 1978, explorer Tim Severin and a four-person crew sailed from Ireland to the United States to faithfully recreate the journey undertaken sometime between AD 512-530 by Brendan the Navigator, said to be the first man to sail across the Atlantic – a thousand years before Columbus and his crew set sail aboard the Nina, the Pinta and the Santa Maria.  

For over 3,000 years, the stone fort of Dún Aonghasa, perched on the cliffside on Inis Mór (Inishmore), has stood firm against the aggressive elements of the Atlantic, and there’s hardly a more evocative fortification anywhere in Ireland.  

It’s not just about an eye-catching location, either: excavations have revealed significant evidence of prehistoric metalworking, as well as several houses and burial sites.  

You arrive first at the visitor centre, where panels provide a detailed history of the site, before walking the 1km to the fort itself. The path is uneven and stony, so be sure to wear comfortable shoes. Stunning views and the fort’s impressive construction are the reward for those who are up for a hearty hike.  

It’s also worth noting that the site is free for those overnighting in some of the island’s accommodations – check when you book. 

Another one of Galway’s group of islands, Inis Bó Finne (Inishbofin Island), still has traces of coastal promontory forts along its cliffsides that date back to the Iron Age. A traditional site of trade and travel just 11km off the Galway coast, Inishbofin has a colourful history. On the one hand, it was once used as a prison for rebel priests; on the other, it was said to be popular with pirates – including Ireland’s infamous Granuaile. 

Cast on a hilltop 250m above sea level toward the tip of Donegal’s Inishowen Peninsula, the Grianán of Aileach is proof that our Iron Age ancestors knew something about prime locations. The views are stunning – Lough Swilly and Lough Foyle are within sight, while on a clear day, the view from the stone fort extends to five counties.  

The fort was built in the 1st century AD to replace an earlier Iron Age hillfort. From the 5th to the 12th century, it served as the seat of the Ui Neills, the royal family of Ulster; inside are a cairn and a holy well. 

Just outside of Kenmare, the Bonane Heritage Park is one of Ireland’s most important archaeological sites. The park is dotted with over 250 well-preserved sites that span over 5,000 years, all the way from the Stone Age through to pre-Famine times. Guided tours of the site are available, but you can also explore the park's features on their 2km looped, including a stone circle, a ringfort, standing stones, a fulacht fiadh and a burned mound thought to be used for cooking from 1500 to 500 BC.  

The National Museum of Ireland, Kildare Street in Dublin is the primary repository of the nation’s cultural heritage. Within its 19th century walls, you’ll find one of the world’s finest collections of Celtic and early Christian art, including St Patrick's Bell, the Tara Brooch and the Ardagh Chalice. 

The museum is also where you’ll find a collection of bog bodies, which are the key exhibits in the Kingship & Sacrifice section. Four bog bodies are kept here – Old Croghan Man and Clonycavan Man (the subjects of The Discovery Series: The Bog Bodies podcast), as well as Gallagh Man and Baronstown West Man. However, they’re not as well-preserved as they were when they were discovered, when there was rudimentary knowledge of how to protect bodies found in the bog.   

Besides a wealth of information about their provenance and the explanation of various theories as to why they were killed, the exhibit is marked by a deep sense of respect for the four men: each is protected by a circular wall that renders the viewing experience a private and personal one.