Types of Castles: The 4 Main Types and How to Tell Them Apart

Ask what the 4 types of castles are and the usual answer is motte and bailey, stone keep, concentric, and the later gun fort or fortified house. Ask for 3 types of castles and the list shrinks to motte and bailey, stone keep and concentric, which is roughly the order they arrived in. Those names cover most medieval castles examples in Britain and Ireland. Add tower houses and you can classify nearly anything on this map before you reach the ticket desk.

Motte and bailey: the earth and timber start

The first wave of castles after the Norman conquest went up fast, from soil and wood. A motte is a raised mound, usually flat on top, carrying a timber tower and a palisade. The bailey is the lower enclosure beside it, ringed by a bank and ditch, where the hall, stables and workshops stood.

Timber rots, so what survives is the shape of the ground. You get a steep green cone with a saucer of flat land attached, and little else. The Motte of Urr in Dumfries and Galloway and Hen Domen in Powys are earthworks of this kind. Plenty of the small grassy mounds on the map never grew past this stage, which is why so many entries have no stone at all.

Stone keeps and shell keeps

A stone keep is the tall tower people picture when they hear the word castle. Walls several feet thick, few openings low down, the entrance raised to first floor level and reached by stairs. Rochester in Kent, Hedingham in Essex and Trim in Meath are big rectangular keeps. Conisbrough in South Yorkshire is a cylinder braced by heavy buttresses.

A shell keep is the easy one to misread. Instead of a tower on the mound, the mound got a ring of stone wall around its rim, with buildings leaning against the inside and an open yard in the middle. From below it looks like a crown of masonry sitting on a hill. Restormel in Cornwall is the clearest circle of the kind, and Totnes in Devon is the same idea at smaller scale. Climb up and find a courtyard rather than stacked floors, and you are in a shell keep.

Concentric castles and layered walls

Concentric castles ring one defence inside another, so anyone who takes the outer wall is stuck in a narrow space overlooked from the higher wall behind it. There is usually no dominant keep. The strength sits in the gatehouses and the wall towers instead.

The best concentric castles examples are in Wales. Beaumaris on Anglesey is the textbook plan, a low outer curtain wrapped round a taller inner square. Caerphilly uses water as part of the scheme, with dams holding back lakes on two sides. Harlech sits on rock, its massive inner gatehouse doing the work a keep would do elsewhere. Walk the gap between two walls and you are standing inside the idea. Browse the full castle index if you want to line up several in one trip.

Tower houses of Scotland and Ireland

Further north and west the fashion ran to tall private towers rather than large garrison castles. A tower house is a vertical stone home: a vaulted basement for storage at the bottom, hall above, bedchambers above that, a parapet on the roof. One door, a narrow stair in the thickness of the wall, small windows where it matters.

Scotland has them in quantity, plain and L shaped and Z shaped, where wings or round towers let defenders cover the walls. Claypotts near Dundee is a crisp Z plan. Craigievar in Aberdeenshire shows the late, decorated version with turrets and corbelling. Smailholm Tower in the Borders is the stripped back raiding country model. Ireland has its own dense population of them, Bunratty, Aughnanure and Dunguaire among the familiar names. Many run as hotels now, which is why a good share of the castle hotels on this site are tower houses.

Artillery forts and later coastal castles

Once guns got heavy, height became a liability. Coastal defences went low and squat, with thick rounded walls to deflect shot and wide platforms for cannon. Deal in Kent and St Mawes in Cornwall are the clean examples, built as tiers of curved bastions. Blackness on the Forth was reworked to carry guns. These get called castles locally, but they answer a different question: not how to hold a lordship, but how to cover a stretch of water.

Castles that are really country houses

Some entries look medieval and are not. Owners with money built or rebuilt in castle dress, with battlements, towers and arrow slits that never faced an arrow. Penrhyn in Gwynedd and Castell Coch near Cardiff are the obvious ones. The clues are windows that are large and evenly spaced, stone that is uniform in colour and cut, battlements in suspiciously good condition, and rooms arranged for a family rather than a garrison.

A field checklist for identifying what you see

• A mound with a flat top and a lower enclosure beside it, no stone: motte and bailey.
• A mound with a ring of wall on top and a yard inside: shell keep.
• One dominant block, very thick walls, a door raised above the ground: stone keep.
• Two walls with a corridor between them and towers along both: concentric.
• A tall narrow tower, one door, stair inside the wall: tower house.
• Low curved walls, broad gun platforms, a view out to sea: artillery fort.
• Even windows, neat battlements, a drive and lawns: a house in castle costume.

The ditch helps too. A dry ditch with a bank thrown up inside it points to an earthwork castle. A wet moat more often belongs to a stone one.

Where to start

Pick a shape, then pick somewhere to try it out. The CastleMapper map on the home page shows every entry by nation and county, and castles near a city lists what sits within reach of wherever you are staying.