Barcelona had the highest population density of Europe in the beginning of the 19th century.

Extention of the city was therefore essential. Ildefons Cerda designed the extension of Barcelona called the Eixample. His designs belie a network-oriented approach far ahead of his time.

His street layout and grid plan were optimized to accommodate different kinds of transportation, gas supply and large-capacity sewers to prevent frequent floods.  Spacious “chamfered corners” achieved by bevelling the corners of the square blocks and making them octagonal to facilitate manoeuvres at intersections double the road surface.

Nowadays 1,200 square-like crossroads permit loading and unloading without impeding the flow of traffic. The Avinguda Diagonal cuts the rationalist grid.