So you’ve successfully bused/metroed/walked/rolled to St. Chapelle and you see a discouraging visitors queue. Here’s my alternative suggestion if you’re there on Sunday.
The Marché aux oiseaux (and lapins!) website says they are open Sundays from 8am to 7 pm. It is a delightful oasis with no cars and is totally wheelchair accessible. A visit to the pet market will restore your spirits. And it is astoundingly **right in the middle** of La Cité.
p.s. If it’s not Sunday you can still enjoy the oasis of the daily flower and plant market in the same location.