3. Pena Palace
Known for: A colorful mix of styles
Looking down on Lisbon from the Sintra Mountains, the eclectic Pena Palace breaks with most castle conventions. Portuguese king Ferdinand II, known as the “artist king,” built the Romanticist castle in the mid-1800s as a mix of Gothic, Moorish, Romanesque, and Manueline styles in vibrant yellows, blues, and reds. Islamic-inspired horseshoe gates deliver visitors to terraces surrounded by towers of all different heights and covered in a dizzying array of window shapes and crenellations.
The Pena Palace is surrounded by the Pena Park, which is just as eclectic as the castle: American sequoias and Australian ferns grow alongside Chinese ginkgos and Japanese cypresses to create a lush fairy tale forest unlike any other. Visitors can look north to see another fortress, the medieval Castle of the Moors, whose ramparts snake across the mountainside.