If you're a first time traveller to Paris, I highly recommend this waling tours company. The "classic walk" is a great tour for beginners. It'll take you to all the major sites giving you an idea of what you'd like to see in more detail later.
Most tours are 4 hrs long and cost about 20 euros. Tour guides are young and full of interesting tid-bits. The office itself is a great source of English language info plus there's free internet.
24, rue Edgar Faure
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