The roundhouse is a type of house with a circular plan, originally built in western Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 before the Roman occupation using walls made either of stone or of wooden posts joined by wattle-and-daub panels and a conical thatched

Thatching

Thatching is the craft of building a roof with dry vegetation such as straw, water reed, sedge , rushes, or heather, layering the vegetation so as to shed water away from the inner roof. It is a very old roofing method and has been used in both tropical and temperate climates...

 roof. Roundhouses ranged in size from less than 5m in diameter to over 15m. In the later part of the 20th century modern designs of roundhouse eco-buildings started to be built using techniques such as cob, Cordwood

Cordwood construction

Cordwood construction is a term used for a natural building method in which "cordwood" or short pieces of debarked tree are laid up crosswise with masonry or cob mixtures to build a wall.-Construction:Walls are usually constructed such that the pieces of wood are "proud" of...

 or straw bale walls

Straw-bale construction

Straw-bale construction is a building method that uses bales of straw as structural elements, building insulation, or both...

 and reciprocal frame

Reciprocal frame

A reciprocal frame is a class of self-supporting structure made of three or more beams and which requires no center support to create roofs, bridges or similar structures.-Construction:...

 green roof

Green roof

A green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems...

s.
Roundhouses have been built in Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 since the Iron Age

British Iron Age

The British Iron Age is a conventional name used in the archaeology of Great Britain, referring to the prehistoric and protohistoric phases of the Iron-Age culture of the main island and the smaller islands, typically excluding prehistoric Ireland, and which had an independent Iron Age culture of...

.