The Palácio de Cristal is a lovely piece of Victorian engineering — a cast-iron and glass pavilion prefabricated in France and assembled in Petrópolis as a gift from Count d'Eu to Princess Isabel. The structure is delicate and elegant, more Kew Gardens than palace, and sits in a small garden that doubles as an outdoor events space.
The building is used today for art exhibitions and cultural events. It is open to the public when events are not running, and the exterior can always be admired. The combination of the crystal structure against the green hills of the Serra da Estrela is striking, especially in the morning light. A short walk from the Museu Imperial.