We see buildings but, do we understand their geometry? This paper is a perceptual approach to the comprehension of architectural composition. As we know, Gestalt Psychology is concerned with the principle of simplicity in our perception, understanding by this the way simple patterns are "easier to see" because we are inherently predisposed to find them. Gestalt principles tell us the characteristics that a figure or group of figures should have to be considered simple: continuity, closure, similarity, proximity, etc. We compose our visual world of the simple elements we find in it. Every shape would in theory be reduced to simple collections of interconnected shapes. But, while simple things are easily visible, and therefore easily comprehensible, there are some kinds of patterns, the complex ones, which are difficult to see and to comprehend. We will focus on those designs that evade to be simplified and that does not allow us to use the Gestalt laws that help us in perceiving normal objects, therefore making us difficult the creation of a mental idea of their composition. This paper is about complexity of conception and difficulty of perception. We will focus on the ways we can "hide" or take out of view the ordering principles of architectural shapes. All ordered structures are susceptible of complication, and in architectural compositions ornament has an important role.