Chartres is less than 100 km southwest of Paris, an easy day trip or a stop on the way to the Loire Valley. Most people come for the cathedral — and the cathedral alone is worth the journey — but the old town around it is genuinely attractive, with half-timbered houses, steep lanes, and good views from the bridges over the Eure.
The cathedral of Chartres is the main reason to come. It is probably the most complete Gothic cathedral in the world, with original 12th- and 13th-century stained glass that has no equal anywhere. The old centre around the cathedral has many fine medieval houses and a pleasant walk along the river.