A great square medieval keep with corner towers, standing right on the shore of Carlingford Lough near Kilkeel. It's a State Care royal castle, free to walk into — with the Mournes at your back and the Cooley mountains across the water.
What you'll see — the tall rectangular keep with its corner towers and crenellated top, the surviving curtain wall and gatehouse, the roofless chambers you can wander inside, and sweeping views over Carlingford Lough to the Mourne and Cooley mountains. It's said to date to the 1230s and thought to be an Anglo-Norman royal castle built to guard the mouth of the lough.
How long — most people spend about an hour walking the keep, the walls and the shoreline setting.
Cost — free to enter. There's a small car park on site; no ticket office.
What to bring — sturdy shoes, a windproof coat and water. It's an open coastal site with no café — Kilkeel is a short drive away for a bite.
Parking & dogs — a small car park by the castle. Dogs on leads are usually fine around a coastal monument like this, but it's worth checking before you set off.
Access is seasonal — check before travelling. The keep is typically only open to go inside on set days over the summer; outside those times you can still view it from the outside. Confirm the current opening before you make the trip.
Open coastal ruin — mind children. Uneven ground, worn steps and low walls throughout, right by the shore — wear sturdy shoes and keep little ones close the whole way round.
Plan your visit
Can I visit? Yes — but check access first.
Greencastle is a State Care historic monument and it's free to enter — there's no ticket office and no booking. The catch is access to go inside the keep: it's typically only opened up on set days over the summer season, and outside those times the gate to the interior may be locked, though you can still walk the grounds and see it from the outside. Reports of the exact days do vary, so it's genuinely worth a quick check before you travel down. There's a small car park on site and a portaloo, and no shop or café.
Small car parkNo café — bring a snackDogs — check firstRight on Carlingford Lough
Two to remember:
Access to go inside the keep is seasonal — check the current opening before you make the trip down, or you may only get the outside view. And it's an open coastal ruin — uneven ground, worn steps and low walls right by the shore, so wear sturdy shoes and keep little ones close.
Before you set off
What to wear & bring
👟Sturdy shoes with gripThe ground is uneven with worn steps — trainers or walking shoes, not sandals.
🧥A windproof coatYou're on the open shore of the lough — it catches the wind even on mild days.
📷A cameraThe keep against the Mournes and the Cooley mountains is a proper photo spot.
💧Water and a snackThere's no café on site, so bring your own for the little ones.
Good to know
Everything before you go
Cost
Free to enter. No ticket office and no online booking — it's a State Care historic monument.
Opening
Access inside the keep is seasonal — typically only open on set days over the summer, with the exterior viewable at other times. Reports of the exact days vary, so please confirm the current opening before you travel.
What you'll see
The great rectangular keep with its corner towers and crenellated top, the surviving curtain wall and gatehouse, the roofless interior chambers, and the views over Carlingford Lough to the Mourne and Cooley mountains.
Food
No café on site. Kilkeel, a short drive away, has cafés, pubs and chip shops.
Dogs
Dogs on leads are usually fine around a coastal monument like this, but it's worth checking before you go.
Parking
A small car park by the castle, with a portaloo on site.
Accessibility
It's a coastal ruin — uneven ground, worn steps and low walls, so access is limited for wheelchairs and anyone who finds walking difficult.
How long
About an hour to walk the keep, the walls and the shoreline setting.
Address
Greencastle, near Kilkeel, Co. Down, BT34 4LR — on the shore of Carlingford Lough, a few miles south-west of Kilkeel.
Questions
Before you go
Can you actually go inside the keep?
Yes, when it's open — you can walk into the roofless chambers and around the walls. But access inside is seasonal, usually only on set days over the summer, and the gate to the interior may be locked at other times. Check the current opening before you make the trip, or you may only get the outside view.
Is it free?
Yes — it's a State Care historic monument and free to enter. There's no ticket office and no booking. Parking is on a small car park by the castle.
Is it uneven or accessible?
It's a genuine coastal ruin, so expect uneven ground, worn steps and low walls throughout — sturdy shoes are a must and little ones need watching. Access is limited for wheelchairs and anyone who finds walking difficult.
Is there a café?
Not on site — just a small car park and a portaloo. Bring water and a snack, and Kilkeel is a short drive away for a proper bite.
Can I bring the dog?
Dogs on leads are usually fine around an open coastal monument like this, but it's best to check before you set off.
How long does it take?
Most people spend about an hour walking the keep, the walls and the shoreline — an easy stop on a Mourne coast day rather than a full outing on its own.
Getting there
Greencastle, near Kilkeel, County Down, BT34 4LR — on the shore of Carlingford Lough a few miles south-west of Kilkeel, with a small car park right by the castle.
Greencastle is thought to be an Anglo-Norman royal castle, built to command the entrance to Carlingford Lough — a mirror to Carlingford Castle standing on the far shore. The core of it, the great rectangular keep with its corner towers, is said to date to the 1230s, raised as the crown pushed its authority down this stretch of coast. It's the reason the little townland around it still carries the name Greencastle today.
Being a royal stronghold on a contested frontier, it saw its share of trouble. It's often said to have been besieged and taken by Edward Bruce during his campaign in Ireland around 1316, knocked about by raids across the following century, and later pressed back into service as a garrison in the Elizabethan wars of the 1590s. Whether every twist happened exactly as the old accounts tell it, standing inside those walls with the lough on one side and the mountains on the other, you can feel why the crown wanted to hold this spot.