Archaeologists have found what they describe as a “major megalithic site in Europe” of standing stones in southern Spain.

The 600-hectare site had been earmarked for an avocado farm, but regional authorities first ordered a survey in light of possible archaeological significance, leading to the discovery of more than 500 standing stones.

The stones were found on land adjacent to the Guadiana river near the southernmost tip of the Spanish-Portuguese border.

Jose Antonio Linares, a researcher at nearby Huelva University and one of the project’s three directors, said: “This is the biggest and most diverse collection of standing stones grouped together in the Iberian peninsula. It is likely that the oldest standing stones at the La Torre-La Janera site were erected during the second half of the sixth or fifth millennium BC.”

“It is a major megalithic site in Europe,” Linares added.

At the site, they found a large number of various types of megaliths, including standing stones, dolmens, mounds, coffin-like stone boxes called cists and various enclosures.

In an article published in Trabajos de Prehistoria, a prehistoric archaeology journal in the Iberian Peninsula, the researchers stated: “Standing stones were the most common finding, with 526 of them still standing or lying on the ground.”

The height of the stones varies between one and three metres and although a vast haul, the finding is still dwarfed by the 3,000 standing stones at Carnac (pictured above) in northwestern France.

Primitiva Bueno, co-director of the project and a prehistory professor at Alcala University near Madrid said: “One of the most striking things was finding such diverse megalithic elements grouped together in one location and how well preserved they were.

“Finding alignments and dolmens on one site is not very common. Here you find everything all together: alignments, cromlechs and dolmens and that is very striking.”

With many of the stones buried, excavation of the site is expected last until at least 2026, but Bueno added that part of the site will be open to visitors.