This list of institutions includes: 1) archives and libraries containing books of polyphony; and 2) institutions related to musicians or other people mentioned in this digital library, including generic institutions without a building or precise geographic location, such as "Capilla de Felipe II" [Philip II's chapel], to associate a musician with a particular music ensemble. In order to avoid duplications, any given institution, such as "Catedral de Salamanca. Archivo", serves both to indicate the location of polyphonic books in its archive/library and the institution where musicians could have worked throughout its history. We use the official title of institutions and sometimes a name may scape a quick perusal of the long list of institutions in alphabetical order; for instance, some monasteries and convents are not found under "Monasterio de... " or "Convento de...", as others, but under "Real Monasterio..." or "Real Convento...". Thus, it may be useful to use the options "Search by type" and/or "Search by location" to make sure that an institution is not listed.