Here is T's impression of the Notre Dam Cathedral - it's very big and you feel very small.
There is a small playground behind the Cathedral so you can stretch out a bit while the kids enjoy themselves.
If you need a food break, there is a small restaurant about 10 minutes walk from the Notre Dam Catherdal in the peaceful Dauphine Square. La Rose de France offers a rare combination of great French cuisine and child friendly staff. Read more here or book your table here.