Orsay is a commune in the Essonne department in Île-de-France in northern France. It is located in the southwestern suburbs of Paris, France, 20.7 km (12.9 mi) from the centre of Paris.

Essonne is a department in the southern part of the Île-de-France region in Northern France. It is named after the river Essonne. In 2019, it had a population of 1,301,659, across 194 communes.