From the Wikipedia page 
Roissy-en-France (French pronunciation: [ʁwasi ɑ̃ fʁɑ̃s]; colloquially simply called Roissy) is a commune in the northeastern suburbs of Paris, France, in the Val-d'Oise department. It is located 20.7 km (12.9 mi) from the center of Paris.
One-quarter of Charles de Gaulle Airport (France's main airport) but none of the terminals is in the commune of Roissy-en-France, which gave its original name to the airport. Later renamed Charles de Gaulle Airport, the airport is still commonly referred to as Roissy Airport in France. The rest of the airport lies on the territory of the commune of Tremblay-en-France and several other communes.