Palácio Nacional de Belém

The salmon-slabbed 16th-century Belém Palace is Portugal's official presidential residence and office (though the country's most recent presidents have chosen to live in their own homes). Tours in Portuguese, English and French are available on Saturday only, with just 150 spots up for grabs (book in advance via phone or email). Alternatively, the small but fascinating Museu da Presidência da República is open most of the week.