Spain and Portugal - Pena Castle - Arched doorway , towers either side.. Part of Box 149 Boswell collection - Portugal and Spain. Sintra is a town within the municipality of Sintra in the Grande Lisboa subregion (Lisbon Region) of Portugal. Owing to its 19th-century Romantic architecture and landscapes, it has become a major tourist centre, visited by many day-trippers who travel from the urbanized suburbs and capital of Lisbon.