Opening Hours on Ile de la Cite
The ile is a residential district and hence roads to and from it are open at all times, however of course some of the major items that you may wish to visit do have their own hours. Here are the major ones:
Notre Dam Cathedral - Daily 9 until 6
Palais de Justice - Monday to Friday during mornings, from 9 until 1PM.
Sainte Chapelle - 9 or 9:30 depending on the season until 5pm