[1] The Mission Revival movement was most popular between 1890 and 1915, in numerous residential, commercial and institutional structures, particularly schools and railroad depots.[2] All of the 21 Franciscan Alta California missions (established 1769–1823), including their chapels and support structures, shared certain design characteristics.[3] The missions' style of necessity and security evolved around an enclosed courtyard, using massive adobe walls with broad unadorned plaster surfaces, limited fenestration and door piercing, low-pitched roofs with projecting wide eaves and non-flammable clay roof tiles, and thick arches springing from piers.Other features included long exterior arcades, an enfilade of interior rooms and halls, semi-independent bell-gables, and at more prosperous missions curved 'Baroque' gables on the principal facade with towers.Contemporary construction materials and practices, earthquake codes, and building uses render the structural and religious architectural components primarily aesthetic decoration, while the service elements such as tile roofing, solar shielding of walls and interiors, and outdoor shade arcades and courtyards are still functional.