Persan sits on the river Oise, about thirty-five kilometres north of Paris, facing Beaumont-sur-Oise across the water. The two towns have grown together along the river, and the old part of Beaumont, with its church and remains of a castle, stands on a hill above the valley.
Just south lies the forest of Carnelle, a large expanse of oak and beech woods covering a hill above the Oise. In the forest stands the Pierre Turquaise, a remarkable Neolithic covered alley grave, one of the best-preserved megalithic monuments in the Paris region. A little to the north-east, at Asnières-sur-Oise, the Abbey of Royaumont was founded in the thirteenth century by Saint Louis. Its cloister, refectory and gardens are beautiful, and the abbey is now a cultural centre with concerts in summer.
As a high point, the forest of Carnelle and the plateaux above the Oise offer views over the valley. The roads through the forest are winding and shady, and the routes across the plateaux are open and fast. Surfaces are generally good, and traffic is light away from the main roads.
Persan has fuel, food and basic services. The Oise valley is a pleasant ride, with riverside villages, old churches and views over the water. To the north, the forests of Chantilly and Ermenonville offer more riding through the woods.