The Harliburg (also Harlyburg or Herlingsberg) is a former imperial castle (Reichsburg) in the Harly Forest, in southeast Lower Saxony, Germany.

The River Oker flows below the castle site to the south and east, around the southeastern end of the Harly Forest.

A section of the A 395 motorway runs past the Harly Forest, a few hundred metres east of the old Harliburg, where it is crossed by the B 241 federal road.

Like the Liebenburg, that stood around 10 km to the northwest, it was intended to threaten the access roads to Goslar, which were held by the Hohenstaufen lord, Philip of Swabia.

At the Diet of Erfurt in 1290, the Bishop of Hildesheim accused Henry the Admirable of Brunswick-Grubenhagen of breaking the Landfriede or "imperial peace" that had been in force since 12834, by tolerating highway robbery by the soldiers garrisoning the castle.