The chapel is at 10 boulevard du Palais, inside the law courts. From April 1 to September 30 the hours are 9am to 7pm. From October 1 to March 31 they are 9am to 5pm. Last access is 30 minutes before closing. It is closed on January 1, May 1 and December 25.
Arrive at the time on the ticket. The monument asks you not to come early. Security can include an identity check, because this is the Palais de Justice. The Palais de Justice bus stop is sometimes not served. Closest rail: Cité on métro line 4, Châtelet on lines 1, 7, 11 and 14, and Saint-Michel on RER B and C. Buses 21, 24, 27, 38, 58, 81, 85 and 96 stop nearby when they are running.
Helmets, aerosols, sharp objects, scissors, glass bottles, bulky bags, scooters, skateboards and rollerblades are prohibited. Confiscated items are not returned. Strollers have to be small enough to fold through the X-ray, and they are not allowed in the upper chapel. The visit is described as accessible for people with reduced mobility; the monument’s accessibility page has the step-free detail.
The lower individual rate is for nationals and residents of more than four months in the European Economic Area. Everyone else pays the higher individual rate in the table. Under-18s are free except in a group. Ages 18 to 25 are free for EU nationals and for regular non-European residents in France, again except in groups. That is a narrower rule than the Louvre’s under-26 EEA rate, so do not assume one free ticket covers the other.