Sintra is a wooded hill range scattered with palaces that out-fantasy each other: the candy-striped Pena on the ridgeline, the Moorish castle walls beside it, and the Quinta da Regaleira’s gardens riddled with tunnels and a spiral initiation well. It is the one day trip every Lisbon itinerary earns.
Take the first train out and go straight up to Pena before the tour buses; book its timed ticket online. Midweek beats weekends by a wide margin, and mist in the morning usually burns off by noon.
Trains leave from Rossio station and take about 40 minutes; from Sintra station, buses loop up to the palaces. Pick two big sights, not four. Sintra punishes over-scheduling.