Theodore and Susan Pound recently bought a house in the Buckhead section of Atlanta designed by the architect Cecil Alexander. Most of the people who saw the house when it was for sale didn't much like it, because the rooms were oddly shaped; the house has a circular plan, which you can see a picture of in the article.
Alexander, when asked why the house was round, said:
My first plans were L’s or squares or rectangles [....] But then I realized those shapes waste so much space — a circle is compact, it gives you the maximum interior room for the minimum amount of exposed wall.
This is true; it's the well-known isoperimetric inequality. It's related to a lot of other geometric inequalities.
But I'm not sure that minimizing wall space is necessarily the way to go. My bedroom is round -- the corner I live on is an acute angle, and so whoever designed the building stuck on a round turret so the building didn't stick out into the intersection and stab people. Also, it's difficult to work with curved walls when you don't have curved furniture.
Finally, in a very dense neighborhood circular houses would waste land; there arinevitably holes between the houses, as in the picture below (taken from Wikipedia)
which take up about ten percent of the space. Atlanta's sprawling enough already; they don't need more wasted land, so they probably shouldn't start building neighborhoods of circular houses close together. However, the house in question is 5,500 square feet on four acres of land, so that's not a problem here.