Alcalá de Henares is compact enough to see on foot in half a day, but rich enough to deserve a full one. The main sights cluster in the historic centre — the Renaissance university building, Cervantes' birthplace, the Archbishop's Palace, the Magistral Cathedral, and the old Roman ruins at Complutum just outside the city walls.
The Calle Mayor, the main pedestrian street running from the train station through the old quarter, sets the tone: colonnaded arcades, sixteenth-century facades, and the relaxed pace of a university city that has been doing this for five centuries. On weekends the city fills with day-trippers from Madrid, but mornings are calm.