Broogh Fort is thought to contain the remains of Celtic roundhouses from the early centuries AD. What remains visible today are a central platform contained within concentric banks and ditches, which are now partly eroded.
Roundhouses were the standard form of housing built in Britain from the Bronze Age throughout the Iron Age, and in some areas well into the Sub Roman period. They used walls made either of stone or of wooden posts joined by wattle-and-daub panels and a conical thatched roof and ranged in size from less than 5m in diameter to over 15m. The Atlantic roundhouse, Broch and Wheelhouse styles were used in Scotland. The remains of many Bronze Age roundhouses can still be found scattered across open heathland, such as Dartmoor, as stone 'hut circles'.
Most of what was assumed about these structures by earlier archaeologists was derived from the layout of the postholes, although a few timbers had been found preserved in bogs. The rest has been postulated by experimental archaeology, which has shown the most likely form and function of the buildings. For example, experiments have shown that a conical roof with a pitch of about 45 degrees would have been the strongest and most efficient design.
Although a central fire would have been lit inside for heating and cooking, there could not have been a smoke hole in the apex of the roof, for this would have caused an updraft that would have rapidly set fire to the thatch. Instead, smoke would have accumulated harmlessly inside the roof space, and slowly leaked out through the thatch.
Access to the sight is not restricted. You are free to enter and wander around. Close the gate behind you, and take note of the sign on the gate.
At the given coordinates you will find a plaque telling you about the site. There are 4 numbers on the plaque. Let these be ABCD. Head back to the gate (Second Waypoint). Before passing through, take a look at the right hand side of the gate, where you will see some nuts. Let the number on the top horizontal be E, and the number on the bottom horizontal be F. Ignore the others.
The final is a short distance away at N54 08.AC(E+(D*B)) W004 34.(E*(A+F)C((D*E)-F)