As a follow up to Hussainboltz's post with the BBC Magazine article, I thought I'd post the link the full Strava Global Heatmap showing the most popular running and cycling routes around the world.
Fascinating!
I suggest changing the "Heatmap style" to either Gray or Yellow - you get a better feel for the stats compared to the default Blue that is shown on the BBC article.
labs.strava.com/heatmap/#10...
Cheers
John