In what today is Galicia, during the Neolithic period, that is, between the years 4,500 and 2,500 BC, took place the construction of thousands of tumuli, that is, burial mounds of earth that possess in their interior different types of constructions - the most well-known, dolmens or megalithic chambers - that were constructed for purpose of receiving collective burials. The burial mounds, like these two of the Cross of Brazil, are the first example of monumental architecture documented in Europe and one of the oldest in the world, since nothing similar had happened in the 4 million previous years of evolution of the human race. The burial mounds or tumuli are a monumental man made product characterized by:

1.- They are manmade involving the mobilization and effort of many people for a funerary purpose. 2.- They were built to be visible in the landscape and to last throughout time.

The society that built these types of monuments had a mixed economic base, centred around the hunting of animals, the harvesting of fruits and, for the first time in the history of mankind, the domestication of animals (dogs, pigs, sheep, ...) and the cultivation of cereals and vegetables.