Dolmen of Guadalperal

The dolmen consists of 150 granite stones, called orthostats, placed in a vertical arrangement to form an ovoid chamber 5 metres (16 ft) in diameter.

The chamber, of the anta type,[clarification needed] a common construction in the west of the Iberian Peninsula, consists of 140 stones and was covered with a mound of earth and gravel.

According to the latest research, the menhir carved with an elongated and wavy engraving is believed to be a representation of the Tagus River as it passes through the area.

[citation needed] The monument was discovered in 1926, during a research and excavation campaign led by the German archaeologist Hugo Obermaier between 1925 and 1927.

Hugo Obermaier's team made reproductions of the engravings, which were published in 1960 by German archaeologists Georg and Vera Leisner.