Berlin wants to show its best side this summer and is calling on tourists to do their bit. That, at least, is the basic idea behind the "BerlinPay" scheme. ADVERTISEMENT ADVERTISEMENT Anyone who takes part, for example by collecting rubbish or supporting social projects, receives benefits in return at museums, participating restaurants or Berlin experiences. Sustainable behaviour by travellers is meant to be visibly rewarded. The concept itself is not new; the original idea comes from