The document discusses the urban expansion and design of Barcelona's Eixample district. It was designed in the mid-19th century by Ildefonso Cerdá to accommodate the growing population and industrialization of Barcelona. Cerdá envisioned a grid-like plan with wide streets and square blocks to allow for light, ventilation, and public spaces. The plan aimed to improve public health and social equality. However, it faced opposition from the bourgeoisie and was initially modified. While it has undergone changes, Cerdá's plan formed the basis of the Eixample district, one of Barcelona's most iconic areas.