Experiencing a city by walking, cycling or swimming is the best way to embrace the benefits of slow travel; it enables visitors to go at their own pace, get off the beaten track and meet the locals along the way. Whether that means swimming in a converted barge in Berlin, freewheeling through Copenhagen on the Tour de France route or discovering Lisbon’s street art on a walking tour, Europe’s city centres are more active, green and adventure-filled than you might think.