The project is set up on the orthogonal structure of the Exhibition site, which regulates the whole site, and is guided through research for the minimal, the synthetic and pragmatic attitude regarding in order to find most economic volume.The volume is reduced into three stratums which integrate with one only gesture the various volumes with light horizontal deviating. These three "stratums" are covered with perforated metal sheets, allowing to, in a filtered view, perceive the variable paint colours of the concrete walls in the background.The hall offers a great flexibility the variation of possible installations and have a variable capacity from 1.000 to 4500 places.