• Book a slot for every kid, even free under 18s, since entry runs through Palais de Justice security and holiday queues get long
• Leave the stroller behind: only small folding ones pass the X-ray and none go up the narrow stairs, so bring a baby carrier
• No scooters or sharp objects, including kids' scooters, scissors and glass bottles; there is no cloakroom and confiscated items are not returned

A Gothic royal chapel from the 1240s, tucked inside the Palais de Justice on the Île de la Cité. The lower chapel has a low, painted blue-and-gold vault. A narrow spiral staircase leads to the upper chapel, where walls of stained glass hold 1,113 scenes from the Bible.

Kids who like spotting details can hunt for kings, animals and battles. Sunny days light the glass best.