Exchange your voucher at any Big Bus stops in Paris before you board. Hop on either of the two routes, Classical Route or Montmarte Route, and start exploring the city.
The bus has audio commentary or a live, English-speaking guide to keep you informed as you ride, and each stop is announced so there’s never any confusion.
Top attractions on the Classical Route include the Eiffel Tower, Louvre-Pyramide, Notre-Dame Cathedral, Champs-Elysées, and Trocadéro. On the Montmarte Route, see the Moulin Rouge, Sacré Coeur, Gare du Nord, and Musée Grevin. Where you go and get off is up to you.
Your 1- or 2-day ticket can be upgraded to include a Seine River cruise or entrance to Arc de Triomphe.