Lord Byron came here in 1809 and declared it "the most beautiful [place] perhaps in the world". Located in the foothills of Portugal's Sintra Mountains, this romantic city is studded with pastel-coloured villas and palaces. A designated UNESCO World Heritage Site, the 19th-century Pena National Palace is considered the city's jewel. Surrounded by extensive parkland, the Moorish fortress - known for whimsical design and sweeping views - is one of the finest examples of fairy-tale Portuguese architecture. Just an hour from Lisbon, Sintra is a great option for a classically romantic break.