Cadalso adds the name "de los Vidrios" Historical milestone · Cadalso de los Vidrios, Sierra Oeste, Madrid The municipality, until then called simply Cadalso, officially added to its name in 1916 the memory of its glass kilns, an industry documented since the Middle Ages that came to supply glassware to the Royal Pharmacy of El Escorial. 1916 Photo: Asqueladd (CC BY-SA 3.0) What to see and do in Cadalso de los Vidrios