Built under the direction of star architect Renzo Piano, the Potsdamer Platz Arkaden is Berlin's flagship shopping centre. The interior—a long, airy passageway spread out over several floors—is impressive, no matter what you may think of the ultra-modern design. The mall houses about 120 shops and 16 places to eat, most of which are not unusual in themselves and can be found all over town, but there is the odd gem, such as a Japanese hairdressing salon. The Arkaden is simply one of those places which you must see at least once.