“Desire lines”, or “desire path”, is an expression increasingly used when referring to urban planning. However, we got used to see this “desire path” traced in flowerbed, fields and woods: they are those paths formed as a consequence of vegetation erosion due to the frequent human passage; in fact, they have been chosen as the best way to go from point A to point B. Mapping out bicycle desire lines allows to understand the most used paths in certain urban areas, and to make them real and safe by building a cycle track. It may happen that the desire paths don’t follow precisely already built streets, but rather that they pass through buildings, courtyards, or through squares and other areas that are not reserved for circulation. That happens because a city street grid is often more ancient than the buildings it contains, that may change and offer new paths to travel through.