I explored the often-overlooked European city with a steampunk island and £27 return flights

IF I had wandered through the centre of Nantes alone, I might not have noticed something peculiar about France’s sixth biggest city. I would have simply gazed appreciatively at the tree-lined boulevards, the grand chateau and the Corinthian-columned opera house. Thanks to a guide, though, I was encouraged to look up at the shop fronts,...