These are funeral monuments. Often, the passage starts lower down at the entrance and goes up towards the chamber. Dolmens remained in use for a long time, many were violated during the course history. Some were used as temples by the romans. Numerous clay statues representing gods and godesses were found in them.
Excavations finds in dolmens include pottery, stone tools, polished axes and jewellery.
They can be seen at Carnac and Vannes museums. Kercado, R'och Feutet, Kermario, and the three dolmens at Mane Kerioned. Scientifically speaking, nobody knows, but the standing stones gave way to the imagination and many theories going from a sign post to phallic symbol. Nowadays, we believe that isolated stones signal a nearby burrial place. Alignments are menhirs placed in parallel lines.