The rapid development of the Argentine economy after 1875 made itself evident in San Nicolás in the reclaiming of riverfront land, where the shore popular with washerwomen became the "Paseo de Julio" (today Leandro Alem Avenue) and lots such as the central artillery field became city parks. The area's network of horse-drawn trolleys gave way in 1913 to the first metro stations in the Southern Hemisphere and renowned institutions such as the Colón and Cervantes Theatres were followed in the 1920s and 1930s by the addition of Diagonal Norte Avenue, landmarks such as the Buenos Aires Central Post Office, and one of the greatest concentrations of popular theatres and cinemas in the world.