The walls of the Medieval new town of Vertavillo, Palencia (Spain)

It was normal for these towns to be walled as a means of protection from possible attack. There are still, in many cases, remains of these defensive walls, although most of them are only small (Peñaflor de Hornija, Vertavillo). In other cases, however, large parts of these walls have been conserved (Urueña). In addition to the walls, there are often also remains of castles or defensive fortresses, as in the cases of Portillo or Madrigal de las Altas Torres.