Rujm el-Hiri (Golan Heights) - Ancient Observatory

Ancient Archaeoastronomy in the Golan Heights

Rujm El-Hiri, megalithic monument in the Golan Heights, ID 16-4007-101
Rujm El-Hiri, megalithic monument in the Golan Heights, ID 16-4007-101. Abraham Graicer; licensed under the Creative Commons Attribution-Share Alike 4.0 International license

Rujm el-Hiri (also called Rogem Hiri or Gilgal Rephaim) is the largest ancient megalithic monument in the near east, located 10 miles (16 kilometers) east of the Sea of Galilee in the western part of the historic Bashan plain of the Golan Heights (a contested area claimed by both Syria and Israel). Located at 2,689 feet (515 meters) above sea level, Rujm el-Hiri is believed to have functioned at least partially as an astronomical observatory.

Key Takeaways: Rujm el-Hiri

  • Ruhm el-Hiri is the largest megalithic monument in the Near East, a site built of some 40,000 tons of basalt rock arranged in concentric circles which once stood up to 8 feet high. 
  • Once thought to have been built during the Bronze Age, recent studies suggest the monument must have been built during the Chalcolithic period, about 3500 BCE.  
  • Although the redating means that the original astronomical suggestions would not have worked, new studies have found new alignments that would have enabled tracking of the solstice. 

Built and used during the late Chalcolithic and Early Bronze Age between 5,500–5,000 years ago, Rujm el-Hiri is made of an estimated 40,000 tons of uncut black volcanic basalt fieldstones piled and wedged into between five and nine concentric rings (depending on how you count them), reaching to 3–8 ft (1 to 2.5 m) high.

Nine Rings at Rujm el-Hiri

The site consists of a central cairn with a set of concentric rings encircling it. The outermost, largest ring (Wall 1) measures 475 ft (145 m) east-west and 500 ft (155 m) north-south. This wall measures consistently between 10.5–10.8 ft (3.2–3.3 m) thick, and in places stands up to 2 m (6 ft) in height. Two openings into the ring are currently blocked by fallen boulders: the northeastern measures some 95 ft ( 29 m) wide; the southeastern opening measures 85 ft (26 m).

Not all of the internal rings are complete; some of them are more oval than Wall 1, and in particular, Wall 3 has a pronounced bulge to the south. Some of the rings are connected by a series of 36 spoke-like walls, which make up chambers, and seem to be randomly spaced. At the center of the innermost ring is a cairn protecting a burial; the cairn and burial came after the initial construction of the rings by perhaps as long as 1,500 years.

The central cairn is an irregular stone heap measuring some 65–80 ft (20–25 m) in diameter and 15–16 ft (4.5–5 m) in height. About and around it is a stack of small to medium sized-stones constructed like a shell around the central cairn. When intact, the appearance of the cairn would have been a stepped, truncated cone.

Dating the Site

Very few artifacts have been recovered from Rujm el-Hiri—limited to pottery fragments from the surface—and the harsh local environment has resulted in the lack of suitable organic materials recovered for radiocarbon dating. Based on the few artifacts recovered at the site, the excavators suggested that the rings were built during the Early Bronze Age, of the 3rd millennium BCE; the cairn was built during the late Bronze Age of the late 2nd millennium.

The huge structure (and a series of dolmens nearby) may be the origin of the myths of the ancient race of giants, mentioned in the Old Testament of the Judeo-Christian bible as led by Og, King of the Bashan. Archaeologist Yonathan Mizrachi and archaeoastronomer Anthony Aveni, studying the structure since the late 1980s, suggested that the possible interpretation: a celestial observatory.

Summer Solstice at Rujm el Hiri

Late 1990s research by Aveni and Mizrachi noted that the entranceway to the center opened on the sunrise of the summer solstice. Other notches in the walls indicate the spring and fall equinoxes. Excavations into the walled chambers did not recover artifacts indicating that the rooms were ever used either for storage or residence. Calculations of when the astronomical alignments would have matched stars support the dating of the rings at having been built at about 3000 BCE +/- 250 years.

Aveni and Mizrachi believed that the walls at Rujm el-Hiri pointed to star-risings for the period and may have been predictors of the rainy season, a crucial bit of information for the sheepherders of the Bashan plain in 3000 BCE.

Redating Rujm el-Hiri and Realigning the Astronomy

More recent and extensive studies were carried on at the site in the 21st century and reported by Michael Freikman and Naomi Porat. These investigations, which included a landscape survey of sites and features within 5 km of the site identified a dense Chalcolithic occupation of some 2,000 people in 50 settlements. At the time, there was a crescent-shaped row of large houses surrounding Rujm el-Hiri, but none were within the immediate vicinity of the monument. Optically-Stimulated Luminescence dating (OSL) supports the new date, with dates falling between the mid-3rd to early 4th millennium BCE.

The new dates mean that the astronomical alignments identified by Aveni and Mizrachi no longer work (because of the sun's progression), Freikman and Porathave discovered a small irregularly shaped opening in the wall of the central cairn that on the solstice would have allowed the sun's rays to enter and strike the large flat stone at the entrance of the central chamber.

Frieikman and Porat also suggest that one focus of the site was on the dormant volcano visible to spectators looking through the northwest gate. The team suggests that the original construction may predate the end of the fifth millennium BCE.

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