As the world's second smallest country and the most densely populated one, Monaco might as well be the most opulent and glam-dense city state as well. At its heart is the Rock of Monaco, that overlooks the Mediterranean Sea & played an important strategic role back in the day. A fun challenge: drive into this country just after the sun sets, walk alongside the race tracks in the dead of the night, and sleep in your rental car by the water until the sun rises. (Which definitely is not what we did). Ahem.