So why not take advantage of a trip to Paris to pop the question?
How does it work?
First, ask yourself in what kind of circumstances you want to propose.
There are two possibilities.
The first is the surprise proposal. We agree on a meeting point. Once you’re comfortable, you propose, and I capture the moment like a paparazzi.

It’s possible that people around you might react and even start applauding! Guaranteed surprise effect!

Then we continue the photo session in Paris, and why not finish with a glass of champagne at a café?
Advantage: Total surprise effect.
Disadvantage: Your fiancée might have preferred to wear something else for the occasion. Handling the unexpected (like crowds) can be more complicated.
The second option is to plan a classic photo session with your fiancée. She will think you’re just taking photos in various places around the city.

However, during the photo session, you propose. The surprise remains intact.
Advantage: This allows me to choose the best setting for your proposal.
When should you propose?
Any season works, of course. However, there are times of the day that are easier to manage.

The ideal time is in the morning, when the streets are not too crowded.