>>You can take pictures of monuments; you can take "general" pictures in the street; you can take pictures of people sitting at the same table as you in a restaurant.
Fun fact of the day: It is in violation of the law to publish a photo of the Eiffel Tower at night without permission, because the visual is under copyright.
A French court ruled in June 1990 that a special lighting display on the tower...was an "original visual creation" protected by copyright. The Court of Cassation, France's judicial court of last resort, upheld the ruling in March 1992. The Société d'exploitation de la tour Eiffel (SETE) now considers any illumination of the tower to be under copyright. As a result, it is no longer legal to publish contemporary photographs of the tower at night without permission in France and some other countries.
Actually, some architects and building owners forbid photography, for intellectual property reasons. Freedom of panorama (http://en.wikipedia.org/wiki/Freedom_of_panorama) can be complicated.