We head to the northern slopes of the Sierra de Guadarrama this morning to Segovia, perched on its triangular rock. We see the Roman aqueduct, one of the finest in existence; however, it was during the 15th century that Segovia reached its golden age. There is time to explore the old town, before continuing across the infinite horizons of the northern Meseta and over the Cantabrica Mountains to the sophisticated resort of Santander. (BB, D)