La Rive Gauche is where the artists, writers and philosophers are --the heart of bohemianism & counterculture. Stroll around, soak it in! Say hi to John for me!
You like ice-cream. And this is one of the oldest and best ice-cream parlors in Paris. It's on the gorgeous Iles St Louis, the oldest Paris neighborhood.
Probably my favorite museum in Paris, mostly filled with Impressionist art. Make sure you go to the top and walk behind the clock. It's a really nice shot.
Traditional tea house with hundreds of teas. Head there when you're tired of walking for a relaxing break. A little touristy, but worth it.
La Hune is a fine art, photography, visual communication, and design bookshop. Highly recommended. Don't buy too many books, they're hard to carry back!
On your way to the Eiffel tower, walk through (and eat) in one of the many excellent restaurants, bakeries, cheesemongers of Rue St-Dominique.
When I was a kid, my grandma used to take me here to rent one of the small boats that you push from one end of the fountain to the other. You'll see. Try it!
La Sorbonne is the most famous university in Paris abroad. It's also where Mai '68 started... Sous les pavés, la plage!
The Catacombes de Paris is an underground ossuary which holds the remains of about six million people. Check their website for opening hours. Lines are LONG.
Out of the way, the BNF is one of the most impressive libraries in the world. Since you like books and architecture, you should swing by.