sentences:  The Tagus passes through the southern border of the region in its path west toward the Atlantic Ocean, draining the waters of the Jarama River (collecting in turn the waters of the Lozoya, the Guadalix, the Manzanares, the Henares and the Tajuña), the Alberche and the Guadarrama in the region.The region also includes the exclave of Dehesa de la Cepeda (part of the municipality of Santa María de la Alameda), a mostly open-area geographically located between the provinces of Ávila and Segovia in the autonomous community of Castile and León.Province of Madrid occupies a surface area of approximately (1.6% of all Spanish territory).