I went to Chantilly by train from Gare Nord for a day trip in the spring, and it was well worth it — the chateau, its grounds and artwork, and the nearby racetrack, where the Thoroughbreds were running that day. I’m a racing fan, so the trip was extra special. (I noticed that there are two racing days at Chantilly in October, on the 5th and 9th.) The afternoon was a little like a Degas painting come to life.