When being in Strasbourg (France) last December to visit friends and family of course we went to the Christmas market and the old cathedral.
You can still go inside, even it's a bit crowded by the visitors, most are tourists.
Inside there's of course the famous round glass window, which is the first thing you will notice in the daytime.
But also the ancient organ at the podest is a relict from former days, where the Catholic Church has plate a bigger role.
You also might be amazed by the old astronomical clock which is showing fantastic mechanical animation every full hour.
It's no better way to get into the old continent like to visit one of the old cathedrals which are some 800 to 1500 years old.