Castle Learning Center Castle Keeps
Castles of Britain


© 1999-2015 by Lise Hull
keep A keep was a self-sufficient structure that castle defenders could retreat to as a last resort during a battle. The keep was originally called a donjon or great tower. In medieval documents the great tower is referred to as "magna turris", and the word "keep" didn't come along in the English literature until the later half of the 16th century. Sometimes the basement of the keep served as a prison, so the word dungeon soon developed as slang for the keep.

There were two basic shapes of a keep, square and round. Almost all early keeps were square or rectangular, and were the easiest and fastest to erect. Square keeps had one major drawback. They could easily be damaged at the corners by undermining or bombardment.

cutaway view of a keep

Then came the development of the round keep. They were very difficult to successfully undermine. Arrows and rocks glanced off the rounded walls. Even in later times, after the invention of cannon, the cannon balls also glanced off the keep walls. The earliest round keep in Great Britain was at New Buckingham Castle, built in 1150.

Even after the military importance of castles changed, keeps were still being built. The role of the keep changed from a last resort stronghold to only a lord's private residence or chamber.

Another type of keep was the hall-keep. These were longer than they were high, and had very thick walls. They combined the castle keep, hall, solar and other chambers. One of the first stone keeps to be built in Great Britain, during the medieval period, was at Chepstow Castle. This was a hall-keep erected in about 1070.

A shell keep was a masonry building completely surrounding the summit of a motte. They were round or polygonal and originated as a replacement of a wooden palisade crowning the motte. These types of keeps were hollow because mottes were not strong enough to bear the weight of a solid tower. The walls varied in height from 20-25ft, and were from 8-10ft thick, strengthened by a buttress and, sometimes, wall-towers.

The interior was usually an open court with surrounding buildings backing onto the walls, and the domestic buildings of the lord were usually placed within the circular enclosure of the shell keep. By the 13th century, these types of keeps had generally replaced the wooden tower on the motte, and often an additional stone gatehouse and towers were inserted into the shell keep. Examples of shell keeps are at: Arundel, Berkhamsted, Brecon, Wiston, Cardiff, Restormel, and other castles.

Yet another type of keep developed, this being the keep-gatehouse. Complete control for the entrance of the castle was gained by combining the gatehouse and keep into one structure. The inner gates were open and closed from within the gate passage, and not from the castle courtyards, providing isolation from the rest of the castle. The living quarters were in the upper floors. Some of the castles having a keep-gatehouse are Richmond, Ludlow, and Newark.

The House Keep, or strong house, became common in the 14th and 15th centuries. It was a high rectangular structure, and often had towers on each corner. The pele tower and Scottish tower houses are simular in looks. The stables, or barn, would be located on the bottom floor, or basement. The living quarters would be on the upper floors, and could only be accessed by a removable wooden ladder. The upper floors would also have very small and narrow windows so that no one could enter via a window.

Castle keeps varied in size. The round keep at Pembroke Castle is four stories, over 53 feet in diameter, 80 feet in height, and has walls 16 feet thick. It is one of the greatest keeps ever built. Here are some other heights and thickness of keeps:

  • Castle Rising Castle: 50 feet high with walls 7 feet thick.
  • Dover Castle: 83 feet high with walls 12 feet thick.
  • Newcastle Castle: 75 feet high with walls 18 feet thick.
  • Norham Castle: 90 feet high with walls 15 feet thick.
  • Kenilworth Castle: 80 feet high with walls 14 feet thick.
The earliest known stone keep built in Great Britain is at Chepstow Castle, built in 1068.