Iron Age – Defensive Hillforts

The age of the Iron Age Hillforts in Wales started sometime around 700BC until around 60AD when the Roman Empire had successfully subdued the local Celtic tribes and chieftains.

Although hillforts are known during the Bronze Age, the golden Age of hilltop fortification took place during the Iron Age. However, some hillforts were still in use during the Roman period. These are known as Romano-British defensive enclosed settlements and it is apparent that most communities quickly settled down under Roman rule.

Hillforts were constructed for defensive purposes. However, there is no clear evidence as to why they were constructed as most were without any source of water and unlikely to have been used as permanent settlements or as long-standing locations for tribal warfare. Although hillforts were designed to withstand a small-scale attack, it is quite probable that they were constructed as a deterrent.

Some historians believe that hillforts were constructed by the Celtic migrants as they settled on territories controlled by the native Britons, or even by the natives to deter the migrating Celts. It has also been suggested that hillforts were a place of tribal gathering, a meeting point for local tribes and a chance for them to show off their power, i.e. the larger the defence the more the power and less likely to be attacked.

Below is a list of all the known Iron Age Hillforts in the area

There are many different kind of hillforts scattered throughout Gwynedd, the most spectacular being Tre’r Ceiri hillfort on Lleyn Peninsula that includes 150 hut circles and the impressive Dinas Dinorwic defensive hillfort, former stronghold of the Ordovices.

I have included an O/S number on all historical sites to enable everyone to locate using an O/S map.


 Maes y Gaer – Iron Age hillfort – Abergwyngregyn SH663725

Pen y Gaer – Iron Age hillfort – Bethesda SH628672

Pen y Gaer - Bethesda

Ty’n Ffridd – Iron Age defended settlement – Rachub SH62826790

Ty'n Ffridd - Iron Age defended settlement Ty'n Ffridd - Iron Age defended settlement

Pen Dinas – Iron Age defended hillfort – Tregarth SH610680

Pen Dinas - Tregarth

Garth Camp – Iron Age hillfort – multi period use (earthwork) – Bangor SH580728

Dinas Camp – small Iron Age promontory fort (also probable Roman) – Felinheli SH518672 (no image)

Crug Camp –  Iron Age / Romano-British – multi period defensive earthwork – Crug House, Bethel SH639653

Dinas Dinorwig – Iron Age hillfort – Llanddeiniolen SH549653

Dinas Dinorwic

Dinas Dinorwic hillfort Dinas Dinorwic hillfort

Pen Dinas Mawr – enclosed defended settlement  – Penisa’r-waun SH553636

Pen Dinas Mawr, Penisarwaun

Caer Carreg y Fran – early Iron Age hillfort – Cwm-y-Glo SH547627Caer Carreg y Fran, Cwm y GloCaer Carreg y Fran Caer Carreg y Fran - showing hut settlement rems.

Dinas Ty Du – Iron Age fortified hillfort – Llanberis SH565609

Dinas Ty Du Hillfort, Llanberis

Dinas Dinoethwy – defensive Iron Age hillfort (probable) – Bontnewydd SH487591 (no image)

Y Gadlys – Iron Age & later medieval defensive fort – Llanwnda SH480579

Dinas Dinlle – Iron Age hillfort – Llandwrog SH436564

Dinas Dinlle  

Foel Hillfort – Iron Age defended enclosure camp – nr Llanllyfni SH450507

Craig y Dinas – Iron Age defensive enclosure – Llanllyfni SH448520

Caer Engan – Iron Age (Celtic) hillfort – Penygroes SH477526

Gelli Ffrydiau – Iron Age defensive hilltop enclosure – Nantlle SH525535

Gelli Ffrydiau, Dyffryn Nantlle

Castell Caerau – Iron Age hillfort – Dolbenmaen SH509439

Craig y Tyddyn – defensive enclosure – Dolbenmaen SH505427

Dinas Emrys – Iron Age / Romano-British / early medieval (rems) Beddgelert SH607491

Dinas Emrys  

Dinas – Iron Age defended hillfort – Beddgelert SH591488

Pen y Gaer – defensive hillfort – (nr Aberglaslyn Pass) Nantmor SH586457 (no image) 


Braich y Dinas – Bronze Age / Iron Age / Roman (destroyed by quarry)Penmaenmawr SH693755

Braich y Dinas, Llanfairfechan

Dinas (Nant y Coed) – Iron Age hillfort – Llanfairfechan SH700738

Dinas Hillfort, Llanfairfechan

Dinas Alltwen – defensive hillfort – Dwygyfylchi SH744772

Alltwen, Conwy

Castell Caer Seion – Iron Age hillfort (60 hut circles)Mynydd y Dref, Conwy SH758777

Dinas Hillfort, Llanfairfechan

Pen y Dinas – large Iron Age hillfort – Great Orme, Llandudno SH779829

Pen Dinas, Great Orme

Cerrig y Ddinas – Iron Age hillfort – Henryd, Conwy SH754739

Caer Bach – early Iron Age hillfort – Rowen SH743730

Caer Bach Hillfort, Rowen

Pen y Gaer – Iron Age hillfort (20 hut circles) – Caerhun SH750692

Pen y Gaer, Caerhun


Tre’r Ceiri – Iron Age hillfort / Romano-British (150 huts circles) – Llanaelhaearn SH373447

Tre'r Ceiri Hillfort  

Pen y Gaer – Iron Age hillfort – Llanaelhaearn SH428455

Carn Pentyrch – Iron Age defensive hillfort – Llangybi, Four Crosses SH424417

Garn Boduan – late Iron Age hillfort (170 hut circles) – Nefyn SH311391

Dinllaen – promontory fort (ruined by golf course) – Morfa Nefyn SH275418 (no image)

Garn Fadrun – Iron Age fort  / Romano-British / early medieval castle (rems) – Tudweiliog SH280350


Garn Saethon – defensive enclosure – (nr Garn Fadrun) Llanfihangel SH298338

Pen y Gaer (Llanbedrog) – Iron Age promontory hillfort – Llanbedrog SH323314 (no image)

Pen y Gaer (Abersoch) – Iron Age defensive hillfort – Abersoch SH298282

Castellmarch / Castell Abersoch – Iron Age defended enclosure – Abersoch SH313285 (no Image)

Castell – Iron Age hillfort – Llanengan SH294267

Pared Mawr /Porth Ceiriad – Iron Age promontory fort – Llanengan SH303246 (no image)

Castell Caeron – Iron Age hillfort – Botwnog SH232303

Conion – Iron Age defensive enclosure – Rhiw SH230283

Creigiau Gwineu – defensive hillfort – Mynydd y Graig, Rhiw SH228274


Castell Odo – Iron Age Celtic hillfort – Aberdaron SH188284


Din Sylwy / Bwrdd Arthur – Iron Age hillfort / Romano-British – Llanddona SH586814

Din Sylwy / Bwrdd Arthur, Llanddona

Dinas Cadnant – Iron Age defensive enclosure (earthwork)– Menai Bridge SH551733

Moel y Don (multi period defensive promontory fort) – (nr) Brynsiencyn  SH516678

Trwyn-y-Parc – Iron Age promontory fort (possible Roman) – Bodorgan SH370650 (no image)

Y Werthyr – Iron Age hillfort (prehistoric) – Bryngwran SH374782

Y Werthyr, Bryngwran

Dinas Porth Ruffydd – Iron Age defensive promontory fort – Trearddur SH225795 (no image)

Dinas Gynfor – Iron Age hillfort – Llanbadrig SH390951

Parciau Hillfort – Iron Age / Romano-British defensive settlement – Benllech SH594847

Dinas Brynteg – possible hillfort enclosure on a natural plateau – Benllech SH499826

Dinas Brynteg (now a golf course)

Some areas may be on private land and permission to roam may be required.
 There are public footpaths leading to most places.
Safety and care must be taken at all times, as some areas are difficult to get to due to hills and slopes that may lead away from paths.