The name Ardennes used in a strict sense refers to the southern half of the area, where the elevations range from 1,150 to 1,640 ft 【350 to 500 m】, though the high point at Botrange, south of Liège, is 2,277 ft. This part consists of sandstone, quartzite, and some slate and limestone. Its rounded summits are separated by shallow depressions containing peat bogs, from which rise many rivers that cut narrow and sinuous valleys. These High Ardennes form the watershed between rivers flowing north and west to the Meuse River and south and east to the Moselle River. Heavy precipitation, combined with low clouds, fog, and frost, make the uplands distinctly bleak. Although one-half of the area is covered by forest, the thin, acid, and waterlogged soil is generally infertile, supporting only heath.

The northern part is much lower, between 655 and 985 ft. Most of the small farmland is under permanent grass for pasture, but there is some cultivation of oats, rye, potatoes, and clover in the valleys. Cattle are raised mainly for dairy production, pigs for the ham that has long been a local specialty of the Ardennes, and sheep for a small wool industry. Cattle hides are processed with the abundant local supplies of tannin from the oak trees. Stone quarrying is widespread, but mining and manufacturing are limited.

Despite a certain raw inhospitality of the area, its economy increasingly depends upon the development of tourism. The Ardennes has one of the lowest population densities of Europe, but it is located in the middle of the heavily populated triangle of Paris-Brussels-Cologne. Mineral springs at Spa, Belg. (whence the English word spa), have made it a favourite health resort since the 16th century. The lonely forests offer respites for central Europeans from the pressures of the surrounding urbanization.

During World Wars I (World War I) and II, the Ardennes became a battleground, the scene of bitter fighting in 1914, 1918, and 1944 (Battle of the Bulge (Bulge, Battle of the); q.v.).