Overview
Two Rock Mountain (Irish: Cnoc Dhá Charraig) rises to 536 m (1,759 ft) and is 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 called Fairy Castle – walkers can sweep their gaze 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 supports red grouse, heathland flora and a patchwork of shallow bog, ferns and gorse on its lower slopes.
History & Name
The summit cairn, a sub‑circular mound of granite and quartz blocks about 27 m across and 3 m high, crowns a Neolithic passage‑tomb that has never been excavated. Locally it is known as Fairy Castle. It is the easternmost example of a chain of summit passage‑tombs that stretch across the Dublin and Wicklow Mountains; from the top you can see the tombs on Montpelier Hill, Tallaght Hill, Saggart Hill and Seahan Mountain.
Older maps label the hill Black Mountain; scholars suggest an earlier Irish name Sliabh Lecga (or Lecca Cenn Sléibe) meaning “the Mountain of the Flagstones”. Archaeologist Christiaan Corlett links this name to the early‑medieval Metrical Dindshenchas and the saga Togail Bruidne Dá Derga, where a “Mount Lecga” is mentioned as a waypoint for raiders.
The south‑eastern slope hosts the Ballyedmonduff wedge tomb, often called the “Giant’s Grave”. Described by John O’Donovan as “the finest pagan grave in any county”, it dates to the Bronze Age and features a three‑chamber gallery, a horseshoe of standing stones and a stone bearing seven cup‑marks. The tomb was first opened in 1832, re‑excavated in 1945 and is now reconstructed for visitors.
Other lost monuments include the Greyhound’s Bed, a long stone cairn destroyed in the 19th century, and a triangular standing stone north‑northeast of Fairy Castle.
A dramatic episode of Irish history is linked to the mountain: in 1591 Red Hugh O’Donnell escaped from Dublin Castle and crossed Two Rock on his way to the O’Toole stronghold at Powerscourt. He was recaptured, but succeeded in a second escape in January 1592, reaching Fiach McHugh O’Byrne in Glenmalure.
Geology & Landscape
The two granite tors that give the mountain its modern name are the best‑preserved examples of tors in the Dublin‑Wicklow range. They were formed by long‑term erosion of muscovite‑microcline porphyritic granite, creating vertical and horizontal joints that weathered into the striking outcrops visible today. The summit plateau is covered by wet and dry heath and blanket bog, providing habitat for the endangered red grouse.
Flora, Fauna & Conservation
The heathland supports a variety of native wildflowers such as heather, bilberry and crowberry. Red grouse (Lagopus lagopus scotica) are a key species; their breeding season runs from March to May, and walkers are asked to keep to the paths to avoid disturbing nests. Skylarks and meadow pipits are common summer visitors, while the bogs provide refuge for ground‑nesting birds. The area is managed by Coillte, which carries out regular heathland restoration to prevent scrub encroachment.
Activities
Walking & Hiking
- Fairy Castle loop – a well‑marked 6 km trail from the Ticknock car‑park to the summit and back, suitable for moderate walkers.
- Two Rock & Three Rock Loop – an 8 km circuit (≈3 h, 393 m ascent) that links Two Rock with neighbouring Three Rock Mountain via the Dublin Mountains Way.
- Dublin Mountains Way – the long‑distance trail traverses the summit, connecting Tibradden and Piperstown to the west and Rathmichael to the east.
- Wicklow Way – runs just west of the summit for walkers extending their route into the Wicklow Mountains.
Mountain Biking
Komoot rates the summit route as a 5‑star mountain‑bike trail. The board‑walked sections through heather and the gentle gradients make it a popular option for cyclists seeking panoramic views.
Wildlife & Photography
The heathland supports red grouse, skylarks and a variety of native wildflowers. Early morning or late‑afternoon light highlights the cairn and the surrounding bog, making the summit a favourite spot for landscape photographers.
Communication Masts & Trig Point
At the top of neighbouring Three Rock Mountain stand a set of television, radio and mobile‑phone masts erected in 1978 by RTÉ to improve reception across the Dublin region. The granite tors on Three Rock give the mountain its name and are a popular photo‑op point.
The summit of Two Rock bears a trigonometrical pillar installed in the 1830s during the first detailed Ordnance Survey of Ireland. The pillar marks the exact surveyed height of the peak and is a useful reference for map‑readers.
Orienteering & Family Activities
A permanent orienteering course winds through the Ticknock forest and the lower slopes of Two Rock, offering a fun challenge for families and school groups. The course is marked on the Dublin Mountains trail map and is maintained by the local orienteering club.
The first 3 km of the Fairy Castle Loop (up to the Three Rock summit) follows a tarmac road and is buggy‑friendly, making it suitable for prams and young children. Picnic tables and a small shelter are located near the Ticknock visitor centre, providing a convenient rest stop.
Practical Information
Access – The mountain is reachable from the Coillte‑managed recreation areas of Ticknock, Kilmashogue and Tibradden. 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.
Parking – Dedicated car‑park (lat 53.253667, lon ‑6.246790) opens 06:00–22:00 daily. The summit itself is at lat 53.239034, lon ‑6.245014.
Opening hours & fees
| Facility | Opening Hours | Admission |
|---|---|---|
| Car‑park | 06:00 – 22:00 | Free |
| Summit area | Open all day | Free |
Accessibility – Trails are well‑maintained but are not wheelchair‑accessible. Sturdy walking shoes are advisable due to occasional rocky sections.
Dog policy – Dogs are welcome but must be kept on a leash because of grazing sheep and ground‑nesting birds.
Family suitability – The walk is moderate; older children generally enjoy it, though it may be challenging for those under 10.
Amenities – The Ticknock visitor centre offers maps, a small café, basic restroom facilities and picnic tables.
Public transport – The most convenient public option is Dublin Bus route 44b, which stops at Ticknock (approximately 30 minutes from the city centre). Services run hourly on weekdays and less frequently at weekends; check the latest timetable before you travel.
Seasonal notes – The hill is popular year‑round. Winter can bring strong winds on exposed sections; summer offers the most reliable footing. Early autumn brings colourful heather and the red‑grouse breeding season.
Nearby Attractions
- Ticknock Forest – a Coillte‑managed woodland with additional walking and mountain‑bike routes.
- Three Rock Mountain – a neighbouring peak with its own tors, TV/radio masts and 360° views, linked by the Dublin Mountains Way.
- Kilmashogue – home to further prehistoric sites, including a wedge tomb and a historic cemetery.
- Powerscourt Estate – reachable via the historic Red Hugh O’Donnell route, offering formal gardens and a waterfall.
Two Rock Mountain offers a rare combination of ancient history, sweeping cityscapes and accessible woodland walking – a perfect half‑day escape for anyone based in Dublin.