I would have never considered going to Chartres if someone in my hostel hadn't told me about it, but I loved going, and would reccomend it to anyone. It's a beautiful little town, about an hour by train from Paris. The train is easy to catch, and it goes through versaille, so you can stop off there, and then catch a later train to chartres. The town is small and very walkable, everything is close by the station. The cathedral is visible from all over and you can pretty much follow it without a map. Today I was there and it was stormy and windy. The cathedral looked so beautiful, but I couldn't figure out how to get in, so I walked around it first. The wind was blowing stronger and stronger, and I finally found the door to get inside. As I opened it, the wind almost blew the door away, and it slammed shut behind me.
The cathedral was almost completely silent, and what struck me first was the incredible vastness of it. The ceilings are high and domed. As i walked a few steps in the organ music started and filled the whole church. Chartres is famous for its stained glass windows, especially the blue color in them. They are beautiful and the detail in them is amazing. I read somewhere that the cathedral is built over an ancient druid worhsipping ground, and lots of their ancient practices influenced the design of the altars and the floor work.
I paid the 2.50 euro to walk up to the bell tower, where you can get an amazing view of the town of chartres. The wind was blowing me almost off the roof, and the clouds were swirling all over the sky, which made everything look very dramatic.
I loved the cathedral in Chartres much more than the Notre Dame of Paris. For one thing it's not such a tourist spot, so there isn't a camera flash going off every few seconds, or a jumble of conversations, or huge lines to get anywhere. It's also beautiful, and the stained glass is truly a wonder.