The Dolmen de Soto is an underground structure in Trigueros, Andalusia, Spain. Also known as the “underground Stonehenge”, this megalithic monument was built between 4,500 and 5,000 years ago and is one of approximately 200 ancient burial sites in Huelva.

The dolmen consists of a circular mound with a long pᴀssage leading to a chamber where eight human remains were found along with various artifacts including cups, bowls, plates, daggers, and marine fossils. But what makes this tomb truly unique is the presence of engravings and paintings on some of the standing stones that line the pᴀssage and chamber. These images depict people, cups, knives, and geometric shapes, and offer a glimpse into the beliefs and practices of the people who built and used this tomb.

The origins of Neolithic tomb construction in Europe remain a mystery. We do know, however, that the Neolithic Revolution began around 10,000 BC in what is now the Middle East, but the development and spread of tomb architecture in Europe is less clear.

By the 5th and 4th millennia BC, pᴀssage tombs became more common, possibly originating from earlier tomb styles in Eastern Europe. The emergence of these stone tombs may have begun in the Iberian Peninsula before spreading northward to areas of Atlantic Europe.

The Dolmen de Soto was discovered in 1923 by Armando de Soto Morillas, who wanted to build a new house on his land. He quickly realized that he had stumbled upon an ancient site and contacted the German archaeologist Hugo Obermaier, who excavated and documented the dolmens between 1924 and 1926.

While Andalusia has around 1,650 such Neolithic burial sites (with around 210 in the province of Huelva alone), the Dolmen de Soto is the most unique of them all because it stands alone, and is different from the more concentrated architectural styles of other places.

Viewed from the outside, these tombs are typically characterized by a circular mound with an east-west entrance leading to an underground pᴀssageway. This pᴀssageway, known as a pᴀssageway, often connects to a designated burial chamber.

In the Dolmen de Soto, the pᴀssageway and chamber form a continuous and gradually expanding gallery. The stone columns inside the pᴀssageway and chamber are carved with megalithic art, often accompanied by schematic images. This art may have been created during construction or, more likely, while the tomb was in use.

In recent years, a team of researchers from Portugal, Spain and the UK has conducted a comprehensive study of the carved and painted stones inside the dolmen. They used a variety of techniques, such as Raman spectroscopy, to record and analyze images that had been largely overlooked by previous scholars.

More than 60% of the dolmen’s vertical columns contain engravings and pigment traces, which were illuminated by pH๏τogrammetry. These images include a variety of motifs, such as circles, daggers, human figures, cups, geometric shapes and circular patterns, providing insights into the changes in Neolithic society, especially in the context of the introduction and use of bronze and bronze weapons.

The team found that some of the engravings were created by reusing an old menhir (large upright stone), while others were created during or after the construction of the dolmens. They also found that some of the paintings were made with red ochre, which was used as a pigment throughout prehistory.

The researchers suggest that these images may have had different meanings and functions depending on their location, orientation, and visibility within the dolmens. The presence of red pigment applied to the engravings suggests a deliberate attempt to enhance the visibility of some of the motifs.

The team is currently trying to determine whether this was done for visual enhancement or whether the paint added to the carvings.

The Dolmen de Soto is open to visitors who want to experience this remarkable site for themselves. The entrance is on the west side of the mound, where a reconstructed gate provides access to the interior. The pᴀssage is approximately 21 metres long and widens from 0.8 metres at the entrance to 3.1 metres wide towards the centre. The chamber is approximately 3.9 metres high and circular in shape. The pᴀssage and chamber are covered with 20 pyramidal stones that form the roof of the dolmen.