These are Medieval citadels or strongholds built between the 17 and 18C to protect the border. Many towns or villages seem to continue to keep guard from their mounted positions or craggy promontories. You must visit Almeida, Castelo Bom, Castelo Melhor, Castelo Mendo, Celorico da Beira, Linhares, Marialva, Penedono, Sabugal and Sortelha in order to see these impressive fortresses.