First translation into English on the occasion of the 150th anniversary of the publication of the General Theory of Urbanization by Ildefons Cerdà, an essential work on urban development.In 1867 Ildefons Cerdà published his 'Teoria general de la urbanització.' In this text, the 'science of building cities', understood as a phenomenon, became a new discipline with a broad economic, social and cultural impact on the life of the people of the city.