Glendalough

An hour and fifteen minutes south of Dublin and you're standing in front of a 10th-century round tower in near-perfect condition, in a glacial valley with two mountain lakes and the quiet of the Wicklow hills. Glendalough — "valley of the two lakes" in Irish — is the single best day trip from Dublin if you have any interest in early medieval history or mountain scenery. It costs nothing to enter.

St Kevin established a monastery here in the 6th century, withdrawing to the valley as a hermit and attracting followers who gradually built a community around him. Kevin is one of the more interesting Irish saints — legend gives him a lifespan of 120 years and a number of characterful episodes involving animals, water and unwanted female attention. The monastery he founded grew through the 7th and 8th centuries into a major centre of learning, producing illuminated manuscripts, training clergy and drawing pilgrims from across Europe. Viking raids in 834 and 836 weakened it; Norman disruption reduced it further; but it survived as an ecclesiastical site until the 16th century.

What survives is substantial. The 30-metre round tower is in near-perfect condition — the conical cap was replaced in the 19th century using original stones found on-site, but the tower stands essentially as built in the 10th century. It served as a bell tower, a refuge during raids (the door is 3.5 metres above ground level, accessed by ladder when needed), and a landmark for pilgrims crossing the Wicklow mountains. The Cathedral of St Peter and Paul — the largest early Irish church building in the country — is roofless but its doorways and carved stonework are intact. St Kevin's Church (the small building with what looks like a chimney on top) retains its stone barrel-vaulted roof after 1,000 years, a structural fact that still impresses engineers. The Priest's House and several smaller oratories complete the monastic enclosure, all free to walk around.

Getting here without a car: St Kevin's Bus Service runs twice daily from Dublin city centre (outside the Mansion House on Dawson Street) directly to Glendalough. The journey takes about 1 hour 15 minutes; return tickets cost around €15. The service runs year-round — book at stkevinbus.com. This is the simplest car-free day trip from Dublin, and the reason Glendalough features on backpacker itineraries while many other heritage sites don't.

The valley has two lakes: the Lower Lake, adjacent to the monastic settlement, and the Upper Lake 2 km further into the valley. The Upper Lake is consistently quieter — tour buses don't always continue that far — and the scenery is more dramatic: high sides, darker water, fewer people. The Spinc ridge trail climbs from the upper lake car park to a ridge with views back over both lakes and deep into the surrounding Wicklow hills — allow 2–3 hours for the full loop. The Wicklow Way, Ireland's first long-distance walking route, passes through the valley.

Arrive before 10am. Tour buses from Dublin arrive from mid-morning and the atmosphere at the monastic site from 11am to 3pm on a summer day is different from the same place at 9am. Laragh village, 2 km east, has budget accommodation (the Glendalough Hostel at Laragh is the main option) and a pub — better positioned for an early start than staying in the car park area.