What defines one atmosphere? Its a difficult question that us, as architects, need to try to answer. In the dictionary definition, atmosphere is a layer of gases surrounding a material body, in this case atmosphere is much more than that. First of all is necessary the understanding of several inter-relationships that helps to create it. The main character of this, is the user, the principal affected, who notice and is influenced for this atmosphere. We can include in this net of relationships, the architecture produced by the man, the nature and another users. In this infinite net we can look since the small scale of relation, until the city scale, if is possible define borders for all the different atmospheres, this borders are blurred and almost imperceptible. Naturally, architecture create spaces and physical separations of spaces, but we can see them like devices to create different atmospheres. Every single detail is important in the construction of one atmosphere, and all these relations between physical things and intangible effects will define it. This should be the first objective for an architect. More than just buildings, what we construct is an atmosphere, and many aren`t even conscious of this. A good architecture creates a good atmosphere, but it can`t be direct perceived. This has never been an easy task, but nowadays, even if is impossible to have an absolute control with this new architecture, we have different tools and new possibilities to try to control and predict many aspects that can be essential in the construction of an atmosphere.