The area of intervention is in a crucial point, that no other city has, in the middle of a valley between two mountains, that represent the upper boundary of BCN. The other limits are the two rivers and the Mediterranean sea. Not very often happen than in a point of the city (two if I include the “symmetric” situation in Llobregat side), for natural reasons, occur so many events in terms of traffic. Taking advantage and the responsibility of acting in a point that indirectly influence the whole city, my project intends to create a huge door-gate of the city. A place dig in very depth, as a hell for cars, where these will be stopped, collected, and reuse in a more functional way that is not the transport. This giant thing comes to be the main brain of BCN, the cars (that in the next future will have a computer inside, so able to elaborate data) will be the oxygen for this super-machine through the power of coordinated computational calculus; in fact, the sum of the capacity of every single car will be multiplied by the number of cars. If oxygen gives activity to the brain, this brain acts (indirectly) with arms; the arms, so, is the GAS ( green active space), the real effect of this machine in the rest of the urbanized area (the main arm is the highway itself that will be a big park). The Gas is a degree upper than simple green we use to know. In the meanwhile, to allow this, the transport will be totally changed from private to public; newlines of subway first of all, much more in numbers and much more frequent; the railroad will be drifted inside it, as well as bus, taxis and car sharing stations as the only wheel transports. In term of architecture, the dig is done under a hill next to Montcada mountain; the hill will be replaced by a naturartificial park that is the roof of the structure and it has the same topography of the hill, but in a fragmented shape to underline the breakage. The immense empty space beneath it is fill by enormous pillars tree shaped; a shape that has various meanings and that is the generalized image of the entire project (pars pro toto; as a single, main element can represent the entire idea of a project). Sezione