If I Was From Paris

I'm busy plotting novels, and researching stuff--including Paris. I'm lucky enough to have visited there a few times, seen the Eiffel Tower, Notre Dame, etc. It's an amazing place, with an amazing history, which is always good for us writers. Did you know for instance that Paris has a whole underground tunnel system? It's patrolled by police, but many corners are still undiscovered, and there's a whole underground culture that lives there.

Fascinating stuff. The February issue of National Geographic has a great feature on these underground tunnels, their history, and even a map. Great for research. It's leaving me hungry for croissants...

How do you research locales for your work?