Troldborg Ring

The Troldborg Ring is an Iron Age fortification in Vejle Municipality in Denmark, 13 km (8.1 mi) west of the city of Vejle. It is located at a natural spring on a high point overlooking the Vejle River Valley. The surrounding area is a steep ravine known as the Devil's Valley (Danish: Fandens Dal). The site consists of a raised area of about 1,700 m² (18,000 sq ft) surrounded by a circular rampart (Danish: ringborg). One side is protected by a steep drop of 70 m (230 ft) to the valley floor, while the other side features a 0.5-metre-deep (1.6 ft), 2.5-metre-wide (8.2 ft) moat.

The Troldborg Ring was built around the years 100-200 during a period of turbulence in Denmark, and it was used until around the year 400. It likely served as a refuge during times of violence rather than a permanent dwelling. It is located 600 m (2,000 ft) north of the former Ravning Bridge over Vejle River, built in 979-980 during the Viking Age. Its placement suggests that the area was strategically important even before the bridge was built. A considerable amount of ash from massive fires has been found at the site, although the source and timing of these fires is unclear.