The project we are working on, and the one we want to present to the Conference, aims precisely to show, from a constructive viewpoint and by means of animation, what the geometry that supports the design and construction of several elements of the Gaudi’s work is. In particular, we are planning to present a video clip showing the constructive control of geometry of one of the Palau Güell’s chimneys. Through the visual capability of the animation, this clip goes to show: how the hat of this chimney is governed by a logarithmic spiral and in which way we can control its construction only by means of a ruler, a set square and some strings.