Okehampton Castle presents a good example of why it was important to consider carefully the location of a castle. The site has steep slopes to the south, providing a natural defence, and the added probability of waterlogged fields to slow down any hostile approaches, and on the northern side there was a wide stream. Norman times saw much violence, and Okehampton Castle had to be a strong fortification with effective defence barriers surrounding it.

Although any substantial documentation about the castle's history is non-existent, there is a mention in the Domesday Book of the first castle to be built at Okehampton, by the Sheriff of Devon, during the late 11th century. This took the form of a motte, or raised mound, with rock-cut ditches around it, which provided the building materials for a stone tower or keep. Few traces of the original castle have survived, but the motte, sporting the fragmentary remains of the 14th century rebuilding of the keep, still tends to dominate the site.

The overall layout of the later castle is quite interesting, as it takes more of an elongated shape, with a northerly gatehouse opening into a long, narrow tunnel known as the Barbican Passage, which restricted access to the main gatehouse within the curtain walls. One of the interesting features in this part of Okehampton Castle are the cobbled areas at the Barbican gatehouse, dating from late 17th century occupation. Cobbles also played a significant part in the kitchen area where a 'screens passage', laid with a cobbled floor, separated the Great Hall from the kitchen in an attempt to lessen the risk of fire spreading. On the eastern side of the site it is possible to identify the ruinous walls of a small chapel still containing a piscina, and adjacent is a terrace of three, first-floor lodgings.

Trying to build up a picture of the past when so little is known, is much like constructing a jigsaw puzzle. At Okehampton Castle searching out the clues about the original construction has proved a challenging task, made more difficult by the frequent changes of ownership and the resulting conversions and extensions to the buildings. From about 1538 there appears to have been limited occupation of Okehampton Castle until the late 1600s, and from then on the buildings were left to decay, and gradually collapse.

Positioned in the very centre of Devon, close to Dartmoor, Okehampton Castle stood as an example of newly-arrived nobility - it was a fortified home, and an important administrative centre. However, it is not thought to have been involved in any raids, nor ever been beseiged.