A guide to the guides to Paris
My answer to A guide to the guides to Paris on Ask MetaFilter
You can’t go wrong with Atlas Obscura. I haven’t used it in Paris (I’ve used it successfully in many other places though, including Mexico City) but from glancing over their listings it looks like there are some real gems there: http://www.atlasobscura.com/things-to-do/paris-france. I’ve been to the Catacombs and they are astonishing.
Then at 23:27:
The excellent Citymapper app knows Paris transport very well.