Nou Barris and Sant Andreu are two neighboring districts located in the northern part of the city, where the river Besòs marks the border with Santa Coloma de Gramenet and Sant Adrià del Besòs. The first one grew during the fifties and sixties with the arrival of the working-class immigration. On the other hand, Sant Andreu is currently undergoing a change due to the construction, in the neighbourhood of La Sagrera, of what is to be one of the two AVE railway stations in Barcelona.