Sintra.

Set against the pine-covered hills of the Serra de Sintra, this UNESCO-listed cultural landscape is a dramatic assembly of palaces, castles, and romantic gardens rather than a single monument. In the 19th century, King Ferdinand II and the Portuguese aristocracy transformed the mountain town into the cradle of European Romantic architecture, leaving behind a dense concentration of historic estates. The result is a whimsical, eclectic mix of Gothic, Moorish, and Renaissance styles. Visitors can explore the colorful towers of Pena Palace, the medieval ramparts of the Moorish Castle, and the initiating wells of Quinta da Regaleira. Because the narrow, winding roads are prone to heavy traffic, arriving by train from Lisbon’s Rossio station is the smartest way to experience this hillside realm.