The Chevreuse valley owes its fame partly to a duchess. Marie de Rohan, Duchess of Chevreuse, was a leading figure in the plots and intrigues of seventeenth-century France, a friend and rival of cardinals and queens, who was exiled several times for her part in conspiracies against Richelieu and Mazarin. The town's name is forever linked with her, and above the roofs the ruins of the medieval castle, called the Château de la Madeleine, still stand on their rock, the remains of a fortress that guarded the valley for centuries.
The Yvette river runs through the town, a quiet stream with weirs and mill races, and the valley is lined with wooded slopes. At about a hundred metres above sea level, it is a green and sheltered trough, and the effect of being in a deep, quiet valley, only half an hour from Paris, is part of the charm. Chevreuse itself has about five thousand people, a pleasant main street, a few cafes and a market, and is an easy place to stop.
A little further east lies the abbey of Port-Royal-des-Champs, near Magny-les-Hameaux, one of the great places of French religious and intellectual history. In the seventeenth century it was the centre of Jansenism, a strict Catholic movement that attracted thinkers such as Blaise Pascal and the playwright Jean Racine, and was bitterly opposed by Louis XIV, who had the abbey destroyed in 1710. The ruins and a museum on the site give a sense of the drama.
The roads of the valley are a joy, winding along the river and climbing over the plateau, with a surface that is mostly smooth and traffic that, outside peak hours, is light. This is among the favourite cycling areas of the Paris region, so expect riders at weekends, and take care on tight bends where visibility is limited. In autumn the leaves can make the road slippery, and on cold mornings frost lingers in the shade.
Saint-Rémy-lès-Chevreuse, a short way along, has more shops and a station, and fuel is available in the larger towns around. The smell of the valley, damp earth, leaf mould and woodsmoke, is a pleasure in itself.