GUADARRAMA from the Latin 'aquae dirrama'. The hydronym became the oronym of the Sierra de Madrid. Another interpretation thinks that the Muslims heard the line of summits of the Long Rope called Guadarrama, today called Bola del Mundo, and will assimilate it to the Arabic Wad al-Rámal, 'river of the sand' and will assign it to two of the rivers that are born of the mountain system alluded to Locality and Spanish municipality located in the northwestern part of the Community of Madrid, 50, 5 kms from the capital of Spain. It has about 20. 000 inhabitants .