The oldest forms of indigenous shelter were often round in shape, something which our ancestors saw reflected in the surrounding natural environment. In the past, they were much more widespread, being the shape of choice because they were strong, good for ventilation and air circulation, energy efficient, less vulnerable in strong winds and they used the least amount of materials relative to floor area. And there is some nifty natural science that makes round buildings more comfortable, more energy-efficient and reliable, especially if you combine the ancient shape with modern materials.
Basic math tells us that a circle encloses the largest area for a given amount of perimeter, hence reducing the amount of material needed for construction. The only reason that houses have been rectangular all these years is that, that is all we could do with the materials we had. Now with modern materials and the reinvention of technology, we can apply to houses the same efficiency of engineering that we apply to suspension bridges and airplanes.
When it comes to house design, the fundamental rule is that a simple shape is much more sustainable than a complex one. And the circle has the shortest boundary relative to its area. This means that for any given floor area a circular house has less wall length, consequently utilising lesser materials. Also, as they have less surface area, relative to floor space, the surface coming in contact with the outside environment is lesser too, reducing heat gain.
In a round house there are dozens of interconnected points which give the building a unique combination of flexibility and strength, qualities which make such structures significantly safer in earthquakes. Moreover, they can cost significantly less to construct. Traditional houses, with their multiple surfaces, are complicated structures. Round houses though, are relatively simpler, using lesser materials and taking reduced amount of time to build time to build. Less surface area eventually leads to lesser maintenance costs over time too.
The beauty of the round design runs deep, be it from the aesthetic point of view, or its environmental responsiveness and energy efficiency.