The Harlyberg, at 255.9 m above sea level (NN), is the highest hill of the Harly Forest, and rises in the district of Goslar in southeastern Lower Saxony, central Germany.

Sometimes the term Harlyberg is used as a synonym for the entire Harly Forest (German: Harly-Wald), but this ignores the fact that there are other summits in that forested hill range.

The hill is located just under 2 kilometres northwest of Vienenburg.

On the summit of the Harlyberg stands the Harly Tower (Harlyturm), an observation tower that was re-opened to tourists in 1986 after decades of decay and following major restoration.

From the observation platforms – one glazed and one open one – of the Harly Tower there are views of the Harz Mountains to the south, the Elm to the north and the Huy to the east.