The Keret House, Poland. The first presentation of Keret House, designed by architect Jakub Szczęsny, was during the WolaArt festival in 2009. It has been described as the 'narrowest house in the world', measuring 133 cm at the widest point and 72 cm at the narrowest.

Image credit: Flickr

The Hang Nga House, Vietnam. Popularly called the 'Crazy House' and resembling a banyan tree, this hotel was designed by architect Đặng Việt Nga. There are five levels, and each room has a different theme. Instead of blueprints, the architect used hand drawings for the design.

Image credit: Kelisi

The Earthship Houses, New Mexico. Designed by Michael Reynolds, 'Earthships' are houses made of recycled materials and have minimum impact on the community. The concept began to take shape in the 1970s, with the aim of creating homes that relied on natural energy.

Image credit: Wikimedia

The Cube Houses, Holland. In the 1970s, the city planners asked architect Piet Blom to build a housing complex overtop a busy road. Thus were born Rotterdam's stunning Cube Houses, tilted at a curious 55 degrees and held up by hexagonal pillars.

Image credit: Paul van de Velde

The Crooked House, Poland. The fairy-tale like Crooked House (Krzywy Domek) was built in 2004 by architects Szotynscy & Zaleski, who took inspiration from the children's book illustrations of Jan Szancer. Its warped walls and stone-elevation decor contribute to its surrealist image.

Image credit: Topory