The Dolmen de Tossen-ar-Run is a Neolithic dolmen located in Brittany, France. It is one of the many dolmens in the region and dates back to around 4000 BCE. The tomb is made up of several large stones that have been arranged in a specific pattern to create a covered passageway and chamber. The dolmen was discovered in the early 20th century and has since been restored for visitors to see.