We visited the Arc de Triomphe in the late afternoon. It's one of the most famous monuments in Paris, which is dedicated to those who fought in the French Revolutionary and Napoleonic Wars. The inside of the arc is inscribed with the names of high-ranking military officials who fought in those wars and the names of the places where battles were won.
With our museum pass we were able to skip the line and head straight inside the Arc, and we climbed more than 280 steps up the small spiral staircase to get to the very top. (By this point in our vacation, we were pros at stair climbing.)
The view from the top of the Arc de Triomphe is pretty spectacular. You get a beautiful view of the Champs-Elysées and the Eiffel Tower. Definitely worth the workout.
The timing of our visit to the Arc was just right. As we were leaving, it was time for the daily ceremony to honor the tomb of the unknown soldier, which rests beneath the center of the Arc. At 6:30 p.m. every evening, the eternal flame that marks the tomb is re-lit. It was an interesting ceremony to watch, and I'm glad we were there to be a part of it that day.
By the way, it is dangerous and nearly impossible to cross the street/rotunda to get to the Arc de Triomphe in the middle of bustling Place Charles de Gaulle. To get to the Arc safely, you must cross under the street. So be on the lookout for signage that points you to stairs that will take you to the tunnel that goes beneath the street to the Arc de Triomphe. It looks like you're heading down to a metro, but it will let you pop out at the center of the monument. (Let my animated GIF below be a warning.)