A group of plans recently found at the Construction Management of the Municipality of Santiago being part of the Official Plan of Urbanization of the Commune of Santiago in scales 1: 5,000 and 7: 7,000 dated in 1939 has enabled to carry out a research that, from representation, studies and analyzes the condition of "modern city" for our capital city. The plans were valid for fifty years in the management of the city's urban development. They find their origins in Karl Brunner's studies and proposals between 7929 and 7932 and in the draft project that made them possible during his second stay in 1934, which Robert Humeres finally developed in the five coming years. The problem we approach in this article is, therefore, related to the capacity of this cartography to contain a specific idea of "modern city". In fact, the thesis of this article is that the Official Plan gives an account of both, an existing city, rigorously registered, and a new one arising as a product of its transformation according to the indications represented on it. In this double intentionality underlies, from our point of view, a clearly "modern" bias, evidenced in both the willingness for understanding the new that comes from the pre-existent phenomenon, as the necessary abstraction its representation should achieve to allow both worlds to cohabitate in the plan. This observation is confirmed when we prove the plan is configured from three types of lines that synthetize the complexity of the public space.