The 1859 Cerdà plan did not foresee the arrival of Diagonal Avenue to the sea.
The construction of a new esplanade above the treatment plant and next to the incinerator and the thermal power plant, in order to organise the 2004 Barcelona Forum, has finally allowed Diagonal Avenue to reach the sea.
As a true proof of the principle of sustainability promoted by the Forum, new homes, hotels and public facilities are now coexisting and integrating a new down-town, previously marginal and frowned upon.
The Forum esplanade, supported by the Forum Building and the Convention Centre, is an extension of Diagonal Avenue in the shape of a hand with open fingers - a delta towards the sea - which covers most of the now expanded sewage treatment plant. Its surface is 14 Ha.
Diagonal Avenue ascends to overcome the Ronda del Litoral from 4.5 m, at its last point with wheeled traffic, up to 17 m, and then begins to descend gently towards the sea. This cover can be seen as a unitary asphalt towel, a giant five-colour patchwork.
On this esplanade chimneys and services of the treatment plant emerge. One of them has become a meteorological and orientation centre. Folded pergolas have been built on the esplanade for shade, as well as two large hypostyle rooms, which coincide with the structure of the sewage treatment plant tanks and support a sawtooth metal structure, the north faces of which are covered with glass, while the south faces are covered with photovoltaic cell panels (6,500 m2). The two rooms without side enclosures are two almost factory ceilings that protect 13,000 m2.
The toes of the esplanade rise so that their ends become cliffs over the areas of the marina, their interstices house steps and ramps. A ha-ha with steps all around the perimeter of the fingers guarantees an uninterrupted horizon by the presence of railings.
The last toe supports a large photovoltaic pergola of 4,500 m2 with four twisted legs, which will be seen as one of the industrial facilities in this area.
The pergola receives sun, produces energy and shade as if it were made of reeds. It is a bias plane of 112x50m, inclined 35 degrees and facing south. It is the last viewpoint-beldevere of the city on the water, which can be reached by descending a flight of steps under a pallium.
The esplanade serves as support and access to the buildings of the 2004 Forum and the Convention Centre, and it also includes in a few fingers-appendages along the coast both the Sailing School and a ship for dry dock, installations of the treatment plant and many services of the marina.
The esplanade extends to the sea through a future sloping park that will bridge the gap between the main square and the beaches.
The approximate surface area of the esplanade is 167,000 m2, with an appendix paved in a northerly direction, which will border the future university buildings and lead to the La Mina neighbourhood, and the stairs lead to the port.
The square-esplanade of the Forum can be understood as a mantle that covers buildings and industrial activities, the form of which - in plan - is the continuation of a Diagonal Avenue that widens and explodes with a series of fingers-appendices as you approach the sea, this being the true end of Diagonal Avenue. This mantle will be the place where multiple, imprecise and unexpected activities can meet in the future.
One of the origins of the project is this figure, from a new Diagonal Avenue stretched out in the shape of a hand, whose fingers open to the sea and through which membrane stairs make it possible to descend to the port.
The sheet-esplanade on the sewage treatment plant seems to have been moved by a wind or a giant wave that has exposed the built volumes of the lower sewage machinery. The sheet accentuates, with folded edges, this condition of mantle independent of the lower buildings.
The last appendix, in the shape of a tail, goes with some freedom towards the zoo and parallel to the sea.
The fingers that end the esplanade are configured as viewpoints-cliffs emerging from the water of the port and facing the distant horizon of the sea.
The edges of the finger-appendages of the esplanade will be defined by the construction of "ha-has", continuous stairs that go down to a perimeter corridor, whose protection railing has a height that reaches the level of the pavement of the finger or appendix. In this way, the presence of the railing is camouflaged and the limits of the fingers are seen as the end of a pier.
The stairs and ramps that descend between the toes to the platform of the pier facilitate pedestrian access to the port.
The tarmac of different colours is proposed as a pavement.
The asphalt pavement will see the extensions that extend it down the stairs to the port and the walkway; like two crossed hands, the one with asphalt fingers and the one with little green fingers.
The boundary elements such as the edges, the "ha-has" and the steps of the stairs will be made of concrete.
The pallium, located as on the future Sailing School, forms with it a unity, both formal and structural. The surface of the photovoltaic pallet is 4000 m2, its slope is 358 and it faces south.
The photovoltaic pergolas, located on the esplanade, cast an extensive shadow over it. They are, in turn, set up as a semi-covered porch, as a hypostyle hall, as if it were the roof of a large market without façades.
The support structure is a direct reflection of the lower structure of the treatment plant, on which it rests.
The image that these pieces will offer, detached -formally and physically- from the elements that make up the esplanade of the 2004 Forum, will allow us to understand them as symbols of the new way of understanding energy and its new role in the construction of the sustainability that the city of Barcelona has set as a challenge today.
The Forum esplanade defines and marks the end of Diagonal Avenue, an avenue that Cerdà did not plan to make it reach the sea and that was blurred against a part of the city that he did not manage to project. To solve this, a 14-hectare space is defined that rises from Llevant Square, which marks the access to the Forum, bypasses the Ronda del Litoral above and, taking advantage of the high elevation, covers a sewage treatment plant located in the area. Civic space coexists with existing infrastructure and creates new ones.
The square extends like a five-coloured tapestry, covers the infrastructure and adapts topographically, descending gently towards the sea. From a bird's eye view, it takes the form of an irregular hand with fingers that enter the sea like a delta. These include facilities such as a sailing school.
Fingers go up gently to use them as stands facing the square. It is shaded and controlled by two hypostyle rooms, a small wooden pergola and a larger one that has become the emblem of the intervention. Both the hypostyle rooms and the large pergola are covered with solar panels that make them a power plant.
The pergola is located at the end of the intervention, above the sea. It casts a porous shadow, like a reed, and its scale is huge. It is supported on four giant concrete pillars, like raised screens, which look like the fingers of the hand, which is the square. It is arranged obliquely, falling into the water with a dynamic and daring gesture which is unique in the city.
The space below the screen is one of the places with the best views over the city of Barcelona.