A roundhouse is a type of house with a circular plan, usually with a conical roof. In the later part of the 20th century, modern designs of roundhouse eco-buildings were constructed with materials such as cob, cordwood or straw bale walls and reciprocal frame green roofs. Europe United Kingdom 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. The people built walls made of either stone or of wooden posts joined by wattle-and-daub panels, and topped with a conical thatched roof. These 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'. Early archeologists determined what they believed were the characteristics of such structures by the layout of the postholes, although a few timbers were found preserved in bogs. The rest has been postulated by experimental archaeology, which has tried different techniques to demonstrate 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. Peter J. Reynolds also demonstrated that, 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 been allowed to accumulate harmlessly inside the roof space, and slowly leak out through the thatch. Many modern simulations of roundhouses have been built, including: Must Farm revelations Much of the earlier supposition was confirmed or denied at a stroke by the finding of a set of Bronze Age roundhouses at the archaeological dig at Must Farm in Cambridgeshire, UK, where samples of all the materials, from posts to walls, to roof were all found, collapsed and charred, but still in situ after 3 000 years. Modern British roundhouses That Roundhouse is an early example of a modern roundhouse dwelling which was built in Pembrokeshire Coast National Park, Wales without planning permission as part of the Brithdir Mawr village which was discovered by the authorities