Two honest options: the C-3/C-8 Cercanías from Atocha or Chamartín to El Escorial (about an hour, then a 15-minute uphill walk or local shuttle to San Lorenzo), or the 661/664 bus from Moncloa interchange — faster at ~50 minutes and it drops you in the upper town.
At 1,000 m the air runs 8–10°C cooler than Madrid: a blessing in summer, a real-coat matter from November to March, when Monte Abantos often shows snow above the domes.
Do the visit in strategic order: the Royal Pantheon first — access closes before general closing time — then the palace floors, the basilica, and Philip II’s startlingly small study, from which the world’s largest empire was administered by memo. The library is the finale: a frescoed vault where the books face spines-in, gilded edges out.
Three hours moves briskly; four is comfortable. It is the largest Renaissance building in the world — pace accordingly, and take the lonja esplanade slowly on the way out.
The afternoon antidote is green: cross into La Herrería’s oak forest and climb to the Silla de Felipe II — the rock seat where the king allegedly watched his monastery rise — for the classic framed view back. It is a signed 8 km round trip from the esplanade, gentle and mostly shaded.
The town earns the overnight: hotels from around €54, terrazas with mountain air, and the monastery esplanade at dawn with nobody on it. Sleepers also inherit the sierra — Cercedilla’s trailheads are thirty minutes on.
Curated picks are coming — meanwhile, the live search covers every bookable property at the same price or better.