When I first looked at The Calls Henge, I didn't realize it was an actual building. To me, it looked like an interesting courtyard structure of some sort. As soon as I read more about it, however, my initial "Oh, that's nice" reaction turned into flat-out amazement.
A submission for the 36 Calls competition, which is actually the address of the proposed site, The Calls Henge was designed by Studiodosi. The spherical, six storey design is covered in ivy plants and boasts solar panels and geothermal pumps to regulate temperature.