Via celsias.com comes these beautiful pictures of a roundhouse in Wales. I hadn't heard of "roundhouses" before but it seems to be a term for an eco-friendly home which can be built very cheaply using traditional (low-tech) methods ... and because of this are often round. The below is from the web site of the family that built it:

You are looking at pictures of our family home in Wales. It was built by myself and my father in law with help from passers by and visiting friends. 4 months after starting we were moved in and cosy. I estimate 1000-1500 man hours and £3000 put in to this point. Not really so much in house buying terms (roughly £60/sq m excluding labour).

The house was built with maximum regard for the environment and by reciprocation gives us a unique opportunity to live close to nature. Being your own (have a go) architect is a lot of fun and allows you to create and enjoy something which is part of yourself and the land rather than, at worst, a mass produced box designed for maximum profit and convenience of the construction industry.

Some key points of the design and construction:

Main tools used: chainsaw, hammer and 1 inch chisel, little else really. Oh and by the way I am not a builder or carpenter, my experience is only having a go at one similar house 2yrs before and a bit of mucking around in between. This kind of building is accessible to anyone. My main relevant skills were being able bodied, having self belief and perseverance and a mate or two to give a lift now and again.

Browse their site for lots more pictures, the story of why their family decided to build a round house and lots of general information about how it was done and how to learn more.