Crystal Palace Park

The Crystal Palace itself stood here from 1854, moved out of Hyde Park after the Great Exhibition, until it burned down one night in 1936. What survived is better: thirty-odd concrete dinosaurs built in 1854, the first anywhere in the world, made before anybody had worked out what dinosaurs actually looked like. They are magnificently wrong and they are still standing by the lake.

Hapoo counts the walk you were doing anyway

Read off your phone's motion sensor after the fact, so there is no start button and nothing running in your pocket. Characters turn up at real park gates across London, this one included.