The free-formed glass roof covers the Courtyard of the Palacio de Comunicaciones in Madrid. The building used to be the main post office of Madrid and serves now as the new town hall of the City of Madrid. Due to the irregular layout of the courtyard a triangular mesh solution for the roof was the most suitable approach and using the idea of the hanging structures. The horizontal cable net that braces the edge beam takes all horizontal reactions of the roof. As a result, mainly vertical reactions are transmitted into the old building.