This is a guest post from Antonina of OpenBuildings - a community-driven and openly editable encyclopaedia of buildings from around the world.
Luc Besson’s 1997 futuristic movie The Fifth Element opens with a breathtaking scene of a multi-level city. The elevated lifestyle pictured there is still more than a few corners around and in everyday architecture rooftops are downgraded to a functionally-obsolete protective part of buildings. However, this line-up of rooftop refuges is a reminder of the fascination of dwelling in the alternative layers of the city. Look around and you will actually discover, apart from the proverbial underground world, every big city also has a rooftop world of its own and it is a most inspiring place to be.