The Arroyo de la Mula, border of two kingdoms Historical milestone · La Cabeza de Béjar, Sierra de Béjar, Salamanca Image of La Cabeza de Béjar, not of the place itself. A document of Alfonso VIII of 1193 fixes as the western boundary of the lands of Ávila the arroyo de la Mula, which rises at the height of Tonda and flows into the Tormes: beyond that stream the Kingdom of León began and that of Castile ended. 1193 Photo: Adolfobrigido (CC BY-SA 4.0) What to see and do in La Cabeza de Béjar