Perhaps a strange place to kick off our list but -bear with us. The Series 9 episode ‘Face the Raven’ not only gave us Jenna Coleman’s ‘exit’ (we’re still getting over that one) but also served to introduce the Diagon Alley of the whoniverse we didn’t even know we’d been waiting for. In the episode, the Doctor and Clara come across a hidden entrance to a secret alleyway -and it actually exists. Walk along Westgate Street and you can actually find the gap in the wall that (probably) leads to a secret, alien street. Neat!