The Jerónimos Monastery in Belém is the greatest achievement of Manueline architecture, Portugal's late Gothic style that incorporated maritime imagery — ropes, coral, anchors, armillary spheres — into an extravagance of carved stone. Work began in 1501 on the proceeds of the spice trade with India, and the building took nearly a century to complete. It is a UNESCO World Heritage Site alongside the Belém Tower.
The church interior is spectacular: slender columns rising to an intricate vaulted ceiling, with the tombs of Vasco da Gama and the poet Luís de Camões in side chapels. The two-storey cloister is the finest in Portugal — walk the upper gallery for the best view of the carved capitals and tracery. The monastery complex includes the Maritime Museum and the National Archaeology Museum. Book tickets in advance in summer; queues can be long.