Sintra is a small hill town 40 minutes by train from Lisbon, and for centuries it was the summer retreat of the Portuguese royal family. Byron called it "glorious Eden" and devoted verses to its mountains and palaces. The UNESCO World Heritage designation it earned in 1995 is well-deserved: the concentration of extraordinary buildings within the national park is matched by almost nowhere else in Europe.
The Sintra National Palace at the centre of town is the oldest — in continuous royal use from the Moorish period until the early 20th century, its two enormous conical kitchen chimneys visible from miles away. High above on the ridge sits Pena Palace, the 19th-century Romanticist extravaganza commissioned by King Ferdinand II in a blaze of yellows and reds. Below Pena, the ruined Moorish Castle walls snake along the ridgeline and offer the best panoramic views of the area. Quinta da Regaleira is the strangest of the estates — its underground initiation well and labyrinthine gardens are unlike anything else in Portugal. Further west, the exotic Monserrate Palace sits in a remarkable botanical garden.
Do not try to see everything in one day. The queues for Pena Palace alone can take an hour in summer. Two days, starting early at each site before the tour groups arrive, is the right amount for a thorough visit.