Question: how far in advance can you book eiffel tower tickets?
Answer: You can buy e-tickets up to 60 days in advance (for lift tickets) and 7 days in advance (for stairs tickets), and book a specific date and time for the lifts (to the second floor or the top of the tower) or the stairs (up until the second floor). This way, you can avoid queueing at the Eiffel Tower ticket offices.