Question about lines/queue at Versailles and the Louvre late July

Yes, of course, there will be a security line. No one is exempt from that. The only line you skip with a pre purchased timed ticket is the ticket buying line. But there is a designated security line for timed ticket holders.

The alternate entrance to the Louvre is likely the Carousel entrance. The Louvre’s website will tell you all the entrances that are open on your day. The main entrance at the pyramid is the busiest. Everyone goes through security. Then you can enter the museum near your appointed time. When going up to the second floor from the main lobby, all escalators lead to the same level. The one by the Denon wing tends to be most crowded. We saw a line just to get on the escalator (in April).

At Versailles, everyone goes through security as you enter the grounds. Then you line up for entrance to the palace. There will be multiple lines, with the entry times posted for each line. At the appointed time, they allow people in to the palace from each line. If you book one of the tours offered by Versailles for €10, there is a separate entrance, so you avoid the entry lines. They ask that you arrive early for the tour (20 minutes?). No one avoids the security lines. You will go through security again to get into the Grand Trianon and the Petite Trianon.

I understand security lines, I was confused after watching a video by a tour company that implied we can skip some line if we buy a tour at Versailles through this private company. I think this is my main question. Does buying a private tour from a company help avoid some lines especially at Versailles?

Everyone goes through the same security lines. Just plan ahead and pay attention. The lines are longer than they need to be because so many pe.ple don't think, just like at the airport. Be ready when it's your turn.

And plan on security at all tourist attractions. Travel light during your sightseeing days.

To answer your question re: Versailles. Yes. We were there a month ago. We booked a small group tour with Walks (website is takewalks). Met the guide at the train station in Paris, rode to Versailles, took a leisurely stroll to the palace, walked up to the gates and saw the LINE. No worries, though, because it was not our line. We were with a tour guide in a small group, she had our tickets reserved, and we were able to enter through the group entrance. We didn't have to wait more than a couple of minutes in line for security.

There were what appeared to be two other lines (the long ones) for individuals not with a group. The lines seemed to move quickly, but they were very long. I'm assuming, but do not know this to be true, that one line was for people who had prebooked tickets and the other was for people who wanted to purchase tickets. In either case, with a small group, you will use a separate entrance with very little wait because your guide gets you there at the right time they have reserved, so you just go in.

I will also say that in 2017 we went with a larger group (bus) tour, and found the same to be true as this year. Group entrance, little wait.

We were at both the end of May with pre-booked timed entry tickets. The security lines at Versailles were better marked e.g. on the hour to the right, on the half hour to the left. I believe the website indicated which side on a specific date. The line security line took about 15 min. It was the same for the Louvre, although the timed ticket entry wasn’t as clearly marked. We lined up next to the Pyramid in the courtyard outside. The staff was pretty good about making sure people in line had tickets and were there for the correct time. That line also took about 15 min.