[RightWhale]

They liked round structures. Well, so do Christians and Muslims. Probably some superstition behind the lack of corners.

[nuconvert]

well, the sun and the moon are round.......

[blam]

Weren't the round houses/graves on the Indo-European steppes called Kurgans.

"The town and the term is Russian for tumulus, the distinctive mound-grave of the nomadic culture to whom the name Kurgan was given."

[Doctor Stochastic]

Circular structures give you greater area to perimeter than do squares. Thus a circular structre needs much less building material than a square one would. It's not as easy to stack boxes in, however.