The Ardennes is a region of extensive forests and rolling hill country (its highest point is under 700 m), primarily in Belgium and Luxembourg, but stretching into France (lending its name to the Ardennes département and the Champagne-Ardenne région) and Germany, where this range is known as the Eifel. Geologically, the Ardennes and Eifel are a volcanic field.

It is an important destination for tourism in Belgium.

The forest has been the location of several battles, such as the Battle of the Ardennes in World War I, and the Battle of France and Battle of the Bulge in World War II. In World War II the allies had considered this area impassible, and therefore defended it weakly, which the Germans used to their advantage.

Its name comes from Arduenna , the Gaulish goddess of hunting.