Barcelona was growing at a prodigious rate. The opening up of Via Laietana and the expansion of the Eixample were soon followed by growth underground: the works to build the metro system were the starting point for a new means of public transport. Urban growth culminated with the annexing of municipalities in the plain around Barcelona: Gràcia, Sant Martí de Provençals, Sant Gervasi de Cassoles, Sants, Les Corts de Sarrià and Sant Andreu de Palomar were incorporated into the city in 1897, followed by Horta in 1904 and Sarrià in 1921.