Große Heuneburg, Iron Age archaeological site in Zwiefalten, Germany.

Große Heuneburg is an early Celtic hillfort on a wooded ridge about two kilometres southwest of Upflamör, a district of Zwiefalten. It consists of a roughly 5-hectare main fort with a trapezoidal plateau 160 to 320 metres on a side, and a nearly square 1.5-hectare annexe to the north, separated by a ditch. Stone walls, covered by earth and vegetation, remain visible in the terrain.

The site was first mentioned in 1827 as Heineburg in a description of the Riedlingen district. In 1921, prehistorian Gerhard Bersu conducted systematic excavations and dated the fortification to the early Celtic period. Excavations that began in 2016 under the Baden-Württemberg State Office for Monument Preservation dated its construction to the 8th to 6th century BC, contemporary with the Alte Burg and the Heuneburg.

The name Heuneburg echoes the nearby Heuneburg at Hundersingen, 12 km south, with which the site is associated. The 1827 description of the Oberamt Riedlingen records it as "Heineburg". The function of the 1.5-hectare annex, or Vorburg, remains unknown; its western rampart may never have been built.

The walls and terraces are overgrown with earth and vegetation but still legible in the terrain; the roughly 130-metre ramparts survive on the east and north sides of the outer enclosure, which has no wall on the west. The site lies about two kilometres southwest of Upflamör on a wooded ridge, reached on foot. Parts of the ramparts were altered in recent times, probably by farming and forestry.

The 2016 excavations uncovered a two-shell dry-stone wall of limestone and a building footprint measuring 9 by 16 metres in the northwest of the main fort. On the eastern side of the outer bailey, a stone-covered earthen rampart was cut into. The site is dated to the 8th to 6th century BC.