Circuit de Mortefontaine, located north of Paris, France, is a historic proving ground and racing circuit originally established in 1929 by the French automotive industry. Initially conceived as a test facility for manufacturers to rigorously evaluate vehicles, it has evolved into a multifaceted venue that hosts a diverse range of motorsport activities.

The circuit's layout is characterized by a high-speed oval, measuring approximately 3 kilometers in length, designed for achieving maximum velocity and conducting aerodynamic tests. Integrated within the oval is a complex network of handling circuits, incorporating various corner types, elevation changes, and surface variations. These sections are designed to simulate real-world driving conditions and assess vehicle handling, braking performance, and overall stability. The arrangement allows for flexible configurations, enabling bespoke circuit designs for specific testing or racing requirements.

Technically, Mortefontaine stands out due to its banked oval sections, which allow for sustained high speeds and create unique cornering challenges. The infield circuits are generally narrow and technical, demanding precision and driver skill. The surface composition varies across the track, ranging from smooth asphalt on the oval to more textured surfaces in the infield, further adding to the testing capabilities. While not a permanent racing venue in the traditional sense, it has hosted various club-level racing events, demonstration runs, and manufacturer testing days.

Mortefontaine's uniqueness stems from its dual-purpose nature as both a proving ground and a racing facility. Its historical significance as a cornerstone of French automotive development, combined with its versatile layout, makes it a distinctive location within the motorsport landscape. The ability to seamlessly transition between high-speed testing and technical handling circuits offers manufacturers and drivers an unparalleled environment for vehicle development and performance evaluation.