The Barrosa dolmen in Portugal, a corridor tomb characteristic of western-Iberian megalithism.

In Europe, megalithic monuments can be found along the length of the Atlantic seaboard, from the south of Spain to the south of Sweden, via Ireland, the western part of Britain, Belgium, the Netherlands, Denmark and northern Germany. Megaliths are also found in the western Mediterranean basin: in Catalonia, in the Balearic Islands, in Corsica and in Sardinia.
Even if megalithic monuments can be found throughout France (even in the Alps), their density, type and age vary greatly from one region to another.
The megalithic monuments of western France (i.e. the territory located to the west of an imaginary line joining Caen and Bordeaux) are outstanding compared to those of other regions in number, variety, size, chronology and ornamentation. 
Megalithic monuments are found mainly in the Caen plain, the Saumur region, along the Vendée coast and inland between Niort and Angoulême. However, Brittany stands out as the main area. Within Brittany, the Morbihan coastal area is where the largest megalithic concentrations can be found.

The great megalithic regions of Europe.