Largest Klein bottle house

The ‘Klein Bottle House’ is a 258-m² weekend home (2,777-ft²) for Australians Donna and Mark Howlett. Constructed 2008, it is the first house to be based on the complex geometry of the Klein bottle mathematical concept, first described in 1882 by German mathematician Felix Klein – a non-orientable surface where there is no clear inside or outside. To move around their extremely convoluted holiday home, the Howletts pass along a dramatic spiral stair which winds around an internal courtyard in order to reach the bedrooms and top level living room. The unusual shape of the house is also intended to make references to the playfulness of being on holiday and to sea-shells. Designed by architectures McBride Charles Ryan from Prahran, Australia, the house won the “World’s Best House” award at the 2009 World Architecture Festival and the Grand Designs prize for “Best International Home” in 2010. The origami-like folded surfaces had to be designed using advanced 3D software, before final construction as a steel frame clad in cement and metal sheet. The central courtyard adds cooling and cross-ventilation, and the home also collects rainwater for the Howletts.