Hagen’s Mountain is a 36.5 m high dune of sand situated near Klaipėda, Smiltynė, about 0.6 km to the west from the New Ferry. On top of the dune is a monument built during the interwar period, dedicated to a famous Prussian physicist and hydro engineer, the leader of the Curonian Spit’s landscapers – Ludwig Hagen. At the end of the 19th century, he wrote about, tested, and perfected the technique of forming a foredune. The words "In memory of Ludwig Hagen, the leader of dune landscaping " are engraved on a modest obelisk in German and Lithuanian languages.

Ludwig Hagen scientifically substantiated and systematized the reinforcement of dunes with the help of vegetation as well as foredune formation, and was himself involved in and led the implementation of his ideas in the northern part of the Curonian Spit. In 1936, grateful residents of Klaipėda region built a modest stone obelisk on the dune in his memory. On the front of the obelisk is the German inscription "Hagen’s Hoh" (Hagen’s Mountain). On the other side of the obelisk, the words "In memory of Ludwig Hagen, the leader of dune landscaping" are engraved in German (in bold) and Lithuanian languages. During World War II, the highest dune near Klaipėda was of strategic significance. This is evident from the surviving traces of trenches and buildings.

In the 19th century Ludwig Hagen (1797-1884) was an honorary citizen of the town of Pilau (now Baltiysk), where he built a port, canals, fortified the shores of the spit, and, from 1869, managed the Prussian Directorate of Construction.

The obelisk marking the dune is located in a busy area, next to the pedestrian and bicycle path. The Lithuanian inscriptions are difficult to read (overgrown with lichens). The German inscriptions are believed to have been updated by German monument preservation enthusiasts.