The
High Fens (; ; ), which were declared a nature reserve in 1957, are an upland area, a plateau region in the province of
Liège, in the east of
Belgium and adjoining parts of
Germany, between the
Ardennes and the
Eifel highlands. The High Fens are the largest nature reserve or park in Belgium, with an area of ; it lies within the German-Belgian
natural park Hohes Venn-Eifel , in the Ardennes. Its highest point, at
above sea level, is the
Signal de Botrange near
Eupen, and also the highest point in Belgium. A tower high was built here that reaches above sea level. The reserve is a rich ecological endowment of Belgium covered with alpine
sphagnum raised bogs (not "fens" as the name would imply) both on the plateau and in the valley basin; the bogs, which are over 10,000 years old, with their unique subalpine flora, fauna and microclimate, are key to the conservation work of the park.