Overview
Two Rock Mountain (Irish: Cnoc Dhá Charraig) rises to 536 m (1,759 ft), making it the highest point in the Dublin Mountains range. Its name comes from the two striking granite tors that dominate the south-eastern slope. From the summit, locally known as Fairy Castle, the view stretches from Tallaght and Howth in the north to Bray Head, Killiney Hill, the Great Sugar Loaf and the Wicklow Mountains in the south. The hill is a working landscape of red-grouse heathland, shallow bog and native woodland, managed by Coillte and the Dublin Mountains Partnership. Through the “Dublin Mountains Makeover” initiative, Coillte Nature and the partnership are currently transitioning commercial spruce plantations into biodiverse, native recreational woodlands.
History & Ancient Monuments
The summit cairn is a sub-circular mound of granite and quartz blocks, measuring roughly 27 m across and 3 m high. It crowns a Neolithic passage-tomb that has never been excavated. Locally called Fairy Castle, it is the easternmost link in a chain of summit tombs stretching across the Dublin and Wicklow ranges. On a clear day, you can trace sightlines to the passage tombs on Montpelier Hill, Tallaght Hill, Saggart Hill and Seahan Mountain.
Older maps refer to the hill as Black Mountain, while scholars propose the earlier Irish name Sliabh Lecga (“Mountain of the Flagstones”). This name appears in the early-medieval Metrical Dindshenchas and the saga Togail Bruidne Dá Derga, where Mount Lecga serves as a waypoint for raiders.
On the south-eastern slope lies the Ballyedmonduff wedge tomb, often called the “Giant’s Grave”. Dating to the Bronze Age, it features a three-chamber gallery, a horseshoe arrangement of standing stones and a capstone bearing seven cup-marks. First opened in 1832 and re-excavated in 1945, the tomb was reconstructed to its current form. Antiquarian John O’Donovan once described it as “the finest pagan grave in any county”. Other lost monuments include the Greyhound’s Bed, a long cairn destroyed in the 19th century, and a triangular standing stone near the summit.
The mountain also played a role in a dramatic episode of Irish history. In 1591, Red Hugh O’Donnell escaped Dublin Castle and crossed Two Rock on his way to the O’Toole stronghold at Powerscourt. Though recaptured, he made a second successful escape in January 1592, reaching Fiach McHugh O’Byrne in Glenmalure. His journey through these hills helped forge the alliance that would define the Nine Years’ War.
Geology & Landscape
The two granite tors that give the mountain its modern name are the best-preserved examples in the Dublin-Wicklow range. They formed through the long-term weathering of muscovite-microcline porphyritic granite, which fractured along vertical and horizontal joints to create the dramatic outcrops visible today. The summit plateau transitions from wet heath to blanket bog, while the lower slopes support a patchwork of ferns, gorse and planted Sitka spruce and pine.
Flora, Fauna & Conservation
The open heathland is a vital habitat for the red grouse, a species protected under Irish law. Their breeding season runs from March to May, and visitors are asked to stick to marked paths to avoid disturbing ground nests. Skylarks and meadow pipits are common in summer, while the bogs provide shelter for a range of invertebrates and wildflowers including heather, bilberry and crowberry. Coillte carries out regular heathland management to prevent scrub encroachment and maintain the open character of the slopes. To encourage community connection with this changing landscape, the Dublin Mountains Partnership hosts regular community hikes and guided wellness walks (launched in partnership with Aware in 2025).
Walking & Trails
Two Rock is accessible via several well-marked routes, with the main trailhead at the Ticknock Forest car park.
- Fairy Castle Loop – A 5.5 km moderate circuit taking roughly 1½ to 2 hours. The first 3 km follows a tarmac road and is suitable for prams and young walkers, before transitioning to gravel and boardwalked sections through the heather.
- Two Rock & Three Rock Loop – An 8 km circuit (approx. 3 hours) that links the summit with neighbouring Three Rock Mountain via the Dublin Mountains Way, adding another 90 m of ascent and panoramic ridge views.
- Dublin Mountains Way – This national long-distance trail crosses the summit, connecting Tibradden and Piperstown to the west with Rathmichael to the east.
- Wicklow Way – Runs just west of the peak for those extending their route deeper into the Wicklow Mountains.
Mountain biking is popular on the forest trails, though riders should check the Dublin Mountains Partnership website before heading out, as sections are occasionally closed for weather-related repairs.
Cultural & Audio Experiences
The area has been the focus of recent arts commissions under the dlr Arts Nature and Place series. Visitors can download the Ticknock: What’s Going On? podcast by artists Listen and Breathe, which explores the forest’s changing landscape over millennia. The audio is timed to match the walking pace from the car park to Fairy Castle. Additionally, Méadhbh O’Connor’s Sky Walkers project features six meditative poems set to ambient soundscapes, designed to be experienced while resting on the summit or Three Rock.
Practical Information
Getting there – From Dublin city centre, head south via Marlay Park. Follow signs to Ticknock Forest, turn right at Ballinteer St. John’s Clubhouse, and continue on the R113 to the Ticknock car park. The most reliable public transport option is Dublin Bus route 44B to Ticknock/Glencullen (weekdays only); check Transport for Ireland for weekend alternatives. For car-free options, see Hikes Near Dublin Without a Car.
Parking & Access – The dedicated car park holds 145 spaces and operates daily from 06:00 to 22:00. Parking is free. The summit coordinates are 53.239034, -6.245014.
Amenities – There are no toilets or bins at the recreation site. Follow Leave No Trace principles: take all litter and dog waste home. The Ticknock entrance area has basic wayfinding maps, but no café or indoor facilities.
Accessibility – The trails are not wheelchair-accessible. The initial 3 km tarmac section is buggy-friendly, but the route to the summit involves steep, uneven ground and boardwalks. Sturdy walking shoes are essential.
Dog policy – Dogs are welcome but must be kept on a short lead at all times due to grazing sheep and ground-nesting birds.
Seasonal notes – The hill is open year-round. Winter brings strong winds on the exposed summit and potential ice on the tors. Summer offers the most stable footing, while early autumn brings peak heather colour and the end of the red-grouse nesting period.
Nearby Attractions
- Ticknock Forest – A network of managed woodlands with additional walking and cycling routes.
- Three Rock Mountain – A neighbouring peak featuring its own granite tors, communication masts and 360° views, easily linked via the Dublin Mountains Way.
- Kilmashogue – Home to further prehistoric sites, including a wedge tomb and a historic cemetery.
- Powerscourt Estate – Accessible via the historic Red Hugh O’Donnell route, offering formal gardens, a 121-metre waterfall and woodland walks.
Start your hike with a charged phone and headphones for the landscape podcast, and time your arrival for late afternoon to catch the city lights flickering on across Dublin Bay as the heather shadows lengthen.