Manhartsberg, Mountain summit in Lower Austria, Austria.

Manhartsberg is a low granite ridge in Lower Austria, reaching around 537 meters above sea level and forming part of the Bohemian massif. Its western slopes are home to the Kamptal-Schönberg nature park, which is recognized as the Kamptal Geopark.

The ridge forms the southeastern edge of the Bohemian massif and has long marked the boundary between the Waldviertel, the quarter above the Manhartsberg, and the Weinviertel, the quarter under it; the Vienna archdiocese's Weinviertel vicariate still bears the name "under the Manhartsberg". Near the highest point stand remains of the World War II radio-jamming position codenamed Zangendorf 4, with two antenna masts over 50 metres tall and three 20-metre wooden towers.

The ridge acts as a natural boundary between the Waldviertel to the north and the Weinviertel to the south, two regions with very different landscapes and local traditions. This contrast is easy to notice while crossing the area, from the forested slopes on one side to the open vineyards on the other.

The area is best explored on foot, with clearly marked trails for walkers of different experience levels. Good hiking shoes and enough water are advisable, especially in warmer months when shade can be limited on the open sections of the ridge.

Above Maissau, the ridge carries rich amethyst deposits, noted in the geological literature of the Manhartsberg. The ridge is also crossed by Landesstraße 1238, built as a natural road along the heights and therefore popular with rally drivers. Near the highest point, remains of the WWII radio-jamming position Zangendorf 4 survive.