Flows of people and goods, another vision of fairgrounds in cities. This project is seeking the critic to make Fairground in cities. In general when we are talking about this typology of buildings, the image of neutral big spaces that can be divided in thousands of small storages in the outskirts of the city occurs our minds. The big problem of this complex is connectivity with the city, because actually there is no. Located outside of the city where the price of the plot is cheaper , it also needs a big space for parking cars, being the only way to get there. The Place, its scale, flows, connectivity, flexibility and hybridization are the main issues to rethink with this project. The site is placed in Warsaw, Poland, in one of the main west/east axes of the city. The plot is a large area, 40mx400m, above the train rails next to the main road. Why there? The city of Warsaw was completely destroyed after the WWII by German Army. In the following years, after the collapse of Hitler Empire, Warsaw was under Soviet domination. During these years the city started to reconstruct itself following the new Soviet principles of the ideal city and architecture was losing its historical image which had existed before WWII. Wide roads, isolated blocks of apartments began to grow in accordance with different urban planning features from the north to the south. In the center they created the Palace of Culture due to the architectural values of Stalin Soviet Union. The west/east axes were completely out of manipulation because of the main train rails of the city split the city in 2 parts before going to the underground. Here is the plot of the proposal. A big area with no social life, dislocated from the city with a huge potential of connectivity and flows of people and goods in the center of the city. Hybrid building. Despite the situation of the proposal, the project is enriched with mixture - dry port, fairground, train station and huge indoor public space are going to be mixed up, creating a new social spot where everything can happen. No parking is required, people can get there by train, tram, metro or even by walk. Goods are coming through containers from different parts of Poland thought trains or ships, avoiding the expensive price of transportation by tracks on the road. Flexibility and connectivity between several spaces with different space and scale characteristics let organizers develop every kind of event very fast, saving money and energy. A public space is gained in the roof, the lobby works like a big indoor square used as a new urban space for the city in winter. How to build such a massive/urban building above the rails including non-stop traffic of passengers and goods traffic? … A pre fabric concrete post/tensioned system is thought to solve the problem of the construction. Huge pieces following the example of Bone’s beams of Fisac are developed in factories outside of the city and transported to the place by train. We could say that the building is being built by itself using the