The Roman Towns and the geometry - Examples of Varatio

This work is proposing some examples of a possible use of the geometry based on rectangular triangles, the varatio,  in the planning of Roman towns. It is known that the planning of them is based on the centuriation, a grid of parallel and perpendicular streets, where the two main axes are the Decumanus and the Cardo. The ratio of the catheti of the rectangular triangles gives the angle the Decumanus is forming with the east-west direction.