Hill of Tara: Why Did Ireland Build a Motorway Through Its Most Sacred Ancient Site?
In spring 2007, crews working on a new Irish motorway uncovered something in a field in County Meath. It was a vast circle of timber post holes. The outer ring measured 80 metres across and the inner ring 16 metres. An entrance avenue pointed to the rising of the Pleiades in the autumn sky.
Archaeologists dated the site to the Iron Age, at least 2,000 years ago. They called it a ceremonial enclosure and a pagan temple. Archaeology magazine later ranked it among the ten most important discoveries of that year.
The site had a name: Lismullin. It lay about two kilometres from the Hill of Tara, the most storied hill in Ireland. The road beside it was the M3, a €680 million, 51-kilometre route from Dublin towards Navan. This guide explains what Tara is, what the crews found, and what visitors can see today.
What Tara Actually Is
The Hill of Tara rises gently above the Meath farmland to about 154 metres. It has no cliffs and no crags. We find its power in the layers of history under the grass.
The oldest monument on the hill is the Mound of the Hostages, a passage tomb from around 3,200 BC. It held the cremated remains of nearly 300 people, laid down over roughly a century. Later generations added 33 Bronze Age burials. The tomb is older than the Pyramids and sits in the same era as Newgrange. Its passage catches the sunrise on 8 November and 4 February, close to the old festivals of Samhain and Imbolc.
More than 20 monuments still show on the hill. Ráith na Rí, the Fort of the Kings, is the largest. Its enclosure measures roughly 1,000 metres around and dates to about 100 BC. The Lia Fáil, the Stone of Destiny, stands on the King’s Seat. Legend names it as the coronation stone of the High Kings.
Irish tradition counts 142 kings who reigned at Tara. Myth also links the wider Boyne landscape to figures such as Aengus Óg. UCD scholar Dr Edel Bhreathnach explains that the title King of Tara carried the highest ritual and political rank on the island. Many Irish people treat the hill as the symbolic heart of ancient Ireland.
The Maps Nobody Had
In 1992, the Discovery Programme began a full study of Tara and its surroundings. The state funds this body to survey and record ancient sites. Its work changed how scholars saw the place.
Before the survey, researchers had recorded about 30 monuments on and around the hill. Geophysical scans, aerial photos and fieldwalking pushed that number to roughly 130. The hill turned out to be the centrepiece of a wider ritual landscape. That landscape ran down into the valleys on either side, including the Tara-Skryne Valley to the south and east.
The hill gave the headline, but the valley held much of the detail. By the late 1990s, planners were drawing a new road line through that same valley.
A Road for a Growing Economy
The old N3 between Dublin and Navan struggled under the traffic of Ireland’s boom years. The National Roads Authority planned a new dual carriageway, later upgraded to a full motorway. It ran from Clonee, near Dublin, up to Kells.
The Tara-Skryne section raised early concerns. In 2004, the Irish Times reported 141 archaeological sites along the whole route. Forty-two of them clustered between Dunshaughlin and Dowdstown, the stretch nearest Tara. That equals one site every 370 metres. Experts put the cost of excavating them at a minimum of €30 million.
An Bord Pleanála approved the route in August 2003. More than 350 academics signed letters against the chosen line. Professor George Eogan, who spent 30 years excavating Knowth, spoke out strongly. Senator Maurice Hayes called the area a single archaeological environment that could suffer lasting damage.
Supporters pointed to the road’s benefits for commuters and for the wider economy. Critics pointed to the number of unrecorded sites in the valley. Both sides agreed on one thing: nobody could say what lay under the fields until the diggers arrived.
What Happened When They Started Digging
Construction began in spring 2006. By the end, crews had recorded 38 new sites along the Tara section alone. The earlier surveys had missed every one of them.
Lismullin appeared in spring 2007. The posts themselves had rotted long ago, but their holes remained in the soil. The entrance avenue showed a deliberate design. Researcher Frank Prendergast later showed that it lined up with the Pleiades. That link tied the building to the farming calendar of the Iron Age.
Officials designated the site a National Monument soon after the find. Campaigners and heritage bodies asked for a change of route. They pointed to a western alternative that would have skirted the valley. Others suggested reopening the Navan-Clonsilla railway, which closed in 1963.
The project did not adopt either option.
Preservation by Record
On 12 June 2007, the Minister for the Environment issued a direction under the National Monuments (Amendment) Act 2004. It ordered the “preservation by record” of Lismullin. That phrase means archaeologists document the site fully before builders remove it.
The campaign to save the valley grew into an international effort. TaraWatch, led by Vincent Salafia, explored a judicial review. The World Monuments Fund placed Tara on its 2008 Watch list of 100 endangered sites. UNESCO voiced concern. Irish-American groups also lobbied for a rethink.
On 23 September 2007, more than 1,500 people gathered on the hill. They formed a human sculpture of a harp, with the words SAVE TARA VALLEY across the grass. The image travelled the world, but the plan stayed the same.
Brussels Steps In
The European Commission opened infringement proceedings against Ireland. It argued that Ireland had not applied EU environmental impact rules correctly. It later took the case to the European Court of Justice over the loss of Lismullin.
Work on the road carried on. The M3 opened on 4 June 2010, and Transport Minister Noel Dempsey led the ceremony. Protesters gathered at several points along the route. One group carried a coffin. Journey times between Dublin and Navan fell.
The Record That Remained
In 2013, the National Roads Authority published Harvesting the Stars: A Pagan Temple at Lismullin, Co. Meath. The book documents the structure, its ritual purpose and the astronomy of its entrance. It is a serious scholarly work.
The authority argued throughout that excavation and recording counted as a form of preservation. It also stressed that the work created knowledge that would not otherwise exist. Critics replied that preservation by record suits unavoidable conflicts. They felt a route with real alternatives did not fit that description.
Joe Fenwick of the Department of Archaeology at NUI Galway made a practical point. The surveys used for approval did not match the known density of the Tara-Skryne Valley. Nobody designed those surveys to find buried timber circles. Crews only found Lismullin because they opened the ground.
The lesson for planners is simple. Deep survey work before a route decision costs less than a rescue dig during construction. Other Irish projects have gone to great lengths for far smaller sites. Builders have rerouted roads around a single fairy thorn tree.
Visiting Tara Today
The Office of Public Works manages the Hill of Tara. Access to the hill costs nothing all year round. A seasonal visitor centre operates from St Patrick’s Church, a 19th-century building at the edge of the site. It offers an audio-visual show and a stained-glass window by Evie Hone. Guided tours run from May to September.
We recommend wearing sturdy shoes, because the grass stays damp for much of the year. We also suggest arriving early, when the low light picks out every bank and ditch. From the crest, you can look across several counties on a clear day. If you look in the right direction, you can also see the M3.
Lismullin no longer exists on the ground. A book, a database and an excavation report preserve it. The road now carries roughly 15,000 vehicles a day. The Mound of the Hostages, the Lia Fáil and the banks of Ráith na Rí all remain.
In our view, Tara rewards a slow visit. We walk the full circuit of Ráith na Rí, then stand at the Mound of the Hostages and read the landscape. Each time we go, we notice a new bank or ditch that we missed before.
Hill of Tara FAQ
Where is the Hill of Tara?
The hill sits in County Meath, about 40 kilometres north-west of Dublin. It lies close to the M3 and near the town of Navan.
Is the Hill of Tara free to visit?
Yes. Access to the hill costs nothing all year. The seasonal visitor centre and guided tours run from May to September.
What is Lismullin?
Lismullin was an Iron Age timber enclosure found in 2007 during M3 construction. Its outer ring measured 80 metres across. Archaeologists recorded it in full before the road replaced it.
How old is the Mound of the Hostages?
The passage tomb dates to around 3,200 BC. That makes it older than the Egyptian Pyramids. It holds the remains of nearly 300 people.
When did the M3 motorway open?
The M3 opened on 4 June 2010. It runs 51 kilometres and cost about €680 million.
The hill is still there, and the earthworks still catch the morning light. They trace the outline of a world that planned carefully what it built and where.
☘️ Join 64,000+ Ireland Lovers
Every Friday, get Ireland’s hidden gems, local secrets, and travel inspiration — the kind you won’t find in any guidebook.
Already subscribed? Download your free Ireland guide (PDF)
Free forever · One email per week · Unsubscribe anytime
Tours & experiences you might love
Powered by Viator. Some links are affiliate links — we may earn a small commission at no extra cost to you.
Secure Your Dream Irish Experience Before It’s Gone!
Planning a trip to Ireland? Don’t let sold-out tours or packed attractions spoil your journey. Iconic experiences like visiting the Cliffs of Moher, exploring the Rock of Cashel, or enjoying a guided walk through Ireland’s ancient past often sell out quickly—especially during peak travel seasons.
Booking in advance guarantees your place and ensures you can fully immerse yourself in the rich culture and breathtaking scenery without stress or disappointment. You’ll also free up time to explore Ireland’s hidden gems and savour those authentic moments that make your trip truly special.
Make the most of your journey—start planning today and secure those must-do experiences before they’re gone!