The Expo 2008’s theme, water and sustainable development, was the starting point for an important group of projects that use water as a raw material to build space. In the Parque del Agua, traditional systems and infrastructures, like channels, waterworks, waterways, purification and seepage basins, are the protagonists of an outstanding landscape with a decidedly didactic point of view about the natural managing of water quality’s improvement. In the urban spaces of the Expo’s area, the system of ponds and waterfalls acts as a link between the different levels of the urbanization and moulds the sinuous shapes of the building that accomodates the pavilions of each participating country. Beside the water-dedicated buildings, like the fluvial Aquarium or the spa, the overall scenario highlights the river Ebro, which, with his dynamic, ecologic and natural features, has contributed early on to create the Expo’s landscape style.

The fluidity in the buildings’ paths and volumes is a recurring feature in spaces where mobility and organization issues are paramount. The Water Tower, for instance, owes a great deal of its form to the search for fluidity, both concerning its external structure and the concept of its circulation spaces, based on the circular ramps that generate its unsettling internal “void”. In the Pabellón Puente designed by Zaha Hadid with Arup, an urban device that’s a great answer to the early plan’s difficulties, it’s impossible to distinguish the bridge’s structure from the building, the front, the roof or from the street level; and a structure is generated in a passageway, which is able to create new and not yet defined uses.