Rue Castex is a wonderful location, close to Bastille and the 11th, while being quite close to St. Paul. It's also walkable to the river. Really a great location. It's in the inner section of a building so it's quite quiet when school is not in session. Everything you need is at hand and you also have the incredible benefit of a dishwasher and a washer–a rarity for a Parisian apartment. Great value.