Try to save Ste-Chapelle for a sunny day, when Paris’ oldest, finest stained glass is at its dazzling best. Enshrined within the Palais de Justice (Law Courts), this gemlike Holy Chapel is Paris’ most exquisite Gothic monument. Ste-Chapelle was built in just six years (compared with nearly 200 years for Notre Dame) and consecrated in 1248. The chapel was conceived by Louis IX to house his personal collection of holy relics, including the famous Holy Crown (now in Notre Dame). Peek at its exterior from across the street, by the law courts’ magnificently gilded 18th-century gate facing rue de Lutèce.

A combined ticket with the Conciergerie costs €12.50.