This 1821 cultural center is home to the United States’ oldest foreign diplomatic mission; it was designated a U.S. National Historic Landmark (the only one in a foreign country unaffiliated with the U.S.). The mansion houses a fascinating museum with a fine collection of paintings and artifacts. Highlights include a section dedicated to the novelist Paul Bowles (who wrote The Sheltering Sky in Tangier), and the displayed correspondence of a hapless American diplomat who was gifted a lion by his Moroccan host.