The hanging Spirals staircase. This design makes sweeping under the stairs easy! A hanging double spiral staircase is part of the Didden Village project in Rotterdam. There are two such staircases; the other is a single spiral.
Theres a special staircase for dogs at this renovated house in Ho Chi Minh City by architecture studio Pets route features narrower treads and shorter risers than the adjacent one for humans, making it more suited to canine strides.