I am familiar with United States laws regarding photography in public places, private land, etc. But I would like to understand the differences between photographing in the US and in France. I am traveling for vacation and will be taking snapshots in as many places as possible. Squares, monuments, churches, museums, street portraits, etc.
In France, you can take a picture of anything in the street, as long as it is in public. Some illumination works are copyrighted, so for example you can't take a picture of the Eiffel Tower by night, because the illumination work is under copyright. You can of course take the picture, but won't be able to sell it without any authorization. That's the same idea for all illuminated monuments in France.
There might be some other limitations, such as government building or stuff like that, and an officer might tell you not to take picture. In Museum, the usage of flash is almost always forbidden. On the street, especially in Paris, you should not use a tripod because, for the law, it can be seen to obstruct the pedestrian circulation.
If you want to shoot portrait, you can, but if you want to exhibit it later, you will need "droit à l'image" from the person that you photograph, only if we can see her face.
Otherwise, you're free to take as much pictures as possible.