Image taken from here
It was presented today, in a congress in Lisbon, a paper about a recently excavated ditch (by Neoépica company) in Lisbon (Travessa das Dores) dating from Late Neolithic and Chalcolithic. It is a large ditch (can reach 8 meters wide and almost 3 meters deep) and was detected in an area highly urbanized, in what seems to be a platform at the middle of a slope over the Tagus river.
The ditch revealed several stone structures and levels of occupation inside it and was abandoned apparently during the middle Chalcolithic.Ditches are, step by step, becoming more frequent in Lisbon peninsula during Recent Prehistory. At the moment it is hard to believe that ditched enclosures will reach there the numbers already available for Alentejo. But the future will bring important news for Estremadura regarding this kind of structures and sites.