Purchase tours for both London and Paris is was the worst decision of my life. Viator buys tickets from a 3rd party company which in turns buys them directly with the company or place you are visiting. By the time you get your tickets Viator and the vendor will all their fees and charges. Example 3 people skip the line Eiffel Tower tickets were $70 with Viator they were $130 and then no one shows up to give them to you so I ended spending another $70 to enter the summit with my Family. Tours that are all walking and not on a bus as you expect (Rain or Shine) for hours and hours only to show you a section that could of been covered with a cab driver in 1/4 the time. Drivers were smelly, late for hours at a time, misleading tour information, Lied about what we were getting vs what actually took place, tickets that are never issued or people don't show up to give you the entrance tickets. I could of done 100 times better purchasing them there with out the 40 to 50% mark up that they pocket. You can book these tours while there from your Hotel or hire Local drivers and you will have a private experience vs being part of a cattle run that they mistreat. TRUST ME DONT USE THEM read all the complaints about them not showing up with tickets or people not getting what they paid for. Talk to your Hotel, Local drivers and buy tickets at the location trust me you will save lots of $$$ and precious vacation time.