We may have a day in Paris en route from an event in Spain to an event in the Netherlands: inbound train arrives about 8 a.m. and we have the option to spend the day and get a late evening train to AMS area instead of taking the mid-morning train onward. This would be in mid-May.

I know nothing about Paris from a visitor's point of view, and wondered if the experts here might offer a few suggestions. We would have to change train stations, so I'm thinking of first going from the first one to Gard du Nord, where we depart from, and storing the bags there would be a good idea in case we're later getting back to than planned.

My companion is very much into the history of the world wars, and sites related to those would be interesting. Marie Antoinette and Co. would hold zero interest, as would romantic Paris. Gourmet dining, also not on the agenda for several reasons, but if you know a good chocolate shop/tea shop/cheese shop, do share! Gardens - yes, galleries - probably not. Eiffel Tower if it's convenient (which I don't know), Notre Dame - ditto. Louvre - probably not feasible.

Also, what's the French for "Where is the loo, please?"