Most people who come to San Lorenzo de El Escorial only see the monastery, that vast granite grid Philip II raised in the second half of the sixteenth century as palace, basilica, library and royal tomb all at once. A short walk below it, through terraced gardens and woodland, sits something far more human in scale. The Casita del Infante, also called the Casita de Arriba, was designed by Juan de Villanueva in the late eighteenth century for the Infante Gabriel, a son of Carlos III, as a place to retreat, play music and escape the endless etiquette of court. Its sibling, the Casita del Príncipe, lies down the hill near the town of El Escorial and was built for the future Carlos IV.
So you have two brothers, two pleasure houses and one of the most severe buildings in Europe looming over both. The contrast is the fun of it. The Casita is neoclassical, elegant and almost modest, with formal gardens and views out over the plain towards Madrid on clear days.
The town sits on the southern slopes of the Sierra de Guadarrama under Monte Abantos, and the roads around it are why Madrid riders know it so well. The M-505 climbs west over the Puerto de la Cruz Verde towards Ávila with fast, flowing bends and granite boulders scattered through pine and oak. Head north and you can link up with the climbs to the Alto del León and Navacerrada, where the air is noticeably colder and snow lingers well into spring. Be aware that on a sunny Sunday morning half of Madrid has the same idea, the Guardia Civil knows it, and speed controls on these roads are common.
Practically it could hardly be easier. San Lorenzo is a proper town of nearly eighteen thousand people, with fuel, cafés and plenty of places to sit under the plane trees on the squares near the monastery. The local speciality worth trying is anything from the Guadarrama mountains in the way of beef or game, and in summer the town is a few degrees cooler than the capital, which is why the royal family came here in the first place. Park in the shade if you can; the granite soaks up heat by afternoon.