Pena Palace is the most photographed monument in Portugal after the Jerónimos Monastery, and it earns that distinction. Perched on the highest point of the Sintra hills at 529 metres, the 19th-century Romanticist palace is visible from Lisbon on a clear day — a riot of colour and competing architectural styles that should be absurd but somehow works. The exterior is painted in bold yellows and reds; the interior preserves the original furnishings and decoration from the period when the royal family used it as a summer retreat.
The setting inside the national park is also magnificent: dense forest surrounds the palace, with views from the ramparts across the Sintra hills and, on clear days, down to the Atlantic coast. The queues in summer can be very long; booking tickets in advance online is strongly recommended. Allow at least two hours for the palace and the walk around the exterior walls.