Amsterdam

The easiest layover city in Europe to get right. Trains from Schiphol's own station reach the city in about 17 minutes, and Centraal puts you straight onto the canal ring, so even five hours on the ground can buy a proper walk. Head south through the Jordaan's narrow canals, cross to the Nine Streets for coffee and cheese shops, and finish at Museumplein if timed tickets for the Rijksmuseum fit your window. A canal boat from near the station covers a lot of ground sitting down. Schiphol's security lines can be long at peak hours, so turn back earlier than feels necessary.