It may sound absurd, but taking a picture of the Eiffel Tower at night and sharing that online may be copyright infringement. The stance is confirmed by the Société d’Exploitation de la Tour Eiffel, who note the following on their website.
“Daytime views from the Eiffel Tower are rights-free. However, its various illuminations are subject to author’s rights as well as brand rights. Usage of these images is subject to prior request from the Société d’Exploitation de la Tour Eiffel.”
A weird and little known quirk of copyright law. So, you can take and sell daytime shots of the Eiffel Tower to places like stock photography sites but not of the night time shots because the evening light show on the tower (which is quite lovely) is copyrighted.