The Naturhistorisches Museum Wien (or Natural History Museum of Vienna) is an extensive and impressive collection based on the collecting passions of Emperor Franz I. After his death his wife, Empress Maria Theresa, gave his collection to the state and allowed it to be opened to the public, and since then the museum has acquired more than 30 million objects, of which 100,000 can be seen in the permanent displays. Ticket lines for the museum can be extremely long, so book in advance to skip the lines!