The aim of our intervention for the convertion of the former Federation of Workers building, projected by the architect César Martinell in 1922, is to protect its best historical value it is the integrity of the volume, a compact inner space and a generous public space, the character of being a singular block in a “industrial” environment it has enough power itself to prevail over the context in a way similar to a church in traditional urban planning. The volume is retro-fitted with the new program required by the public administration as civic center and theatre. Obviously the old modernist main facade and the stairs are preserved restored and integrated in the brand new structure. The historical acces and the new one are not allined to remark the difference between the old and new. The exterior materials are the same old bricks, instead in the interior there is a prevalence of bright and light white tones, plaster and concrete.