If they go to Chartre tell them to visit the cathedral to take a look at the stained glass windows. Absolutely amazing.
I think you are thinking of Chartres, which is 60 miles east'ish towards Paris.
As opposed to La Chartre-sur-le-Loir which is where the Hotel de France is, which is where AM were based during the David Brown years.
Oops, that's the one, my mistake