I spent my second day in Paris exploring the 4th, 5th, and 6th arrondissements. In chronological order, I visited: the Mosque of Paris; El Jardin des Plantes & The Museum of Natural History; The Pantheon; Shakespeare & Co. Bookstore; Notre Dame; and Ile de Saint Louis. Although it sounds like a lot to do in a day (on foot), Paris is actually very pedestrian friendly. Once the metro took me…