“Our Lady of Communications”: that is how Leon Trotsky, when he visited the Spanish capital, christened with irony the monumental building erected by Antonio Palacios and Joaquín Otamendi in the year 1919, and which the people of Madrid have ever since then considered a symbol of their city, to the point of transferring City Hall there in 2007. Such a change of use has come with function and representation problems, and these, precisely, provided the cues for an overhaul of several interconnected interior spaces. First, the entrance is a functional and symbolic doorway, and presents structures of stainless steel and glass that serve as a transparent film between the edifice and the city. Behind this is the information counter, with luminaires suspended over them that are an attraction in the iconic space of the historical operations hall. Then, finally, comes the central nave, surrounded by an ambulatory that leads to the rest of the building’s premises and services, and dominated by a system of curtains that allows flexible use of the space.