the Royal Parks of London. Especially when it's the easiest thing in the world to hire a Barclays bike (which are also so affordable)! We had planned to hire them for a couple of hours thinking that's how long we would need to explore every corner of the park, however, we only needed them for just one hour because cycling is so much more efficient than walking. I don't know why I don't do it more often! It's my new favourite mode of transport!