This paper tries to give notice of some works which are taken place in Europa, concretely in Madrid. One of them is the Canaleja's block. Thinking about it, what is done and what are the final objectives, you can see how necessary is to explain some concepts and how criteria must guide interventions in historic buildings. We must discern the difference between Conservation, Restoration ...and compatible uses. New uses have social and economics objectives, and so frequently destroy important values of restored buildings. We must figh so that it doesn't happens.