A national monument by decree of 1910, Penela Castle is a medieval fortress with origins in the 11th century, founded by D. Sesnando Davides.
D. Sesnando became governor of the territories south of the river Douro after the capture of Coimbra in 1064 by order of Fernando I of Leon the Great, great-grandfather of King Afonso Henriques.
Included in the defensive line of the Mondego, its walls are 19 metres high and have undergone several adaptations, extensions and remodellings over the centuries.
The oldest part of the fortress, the small Fernandino (from Fernando) Sesnandine castle, later became a watchtower (castelejo).
In its walls, with superb views over the Serra da Lousã, we can see arrowholes, openings that are central to surveillance and defence, being used for the throwing of arrows and the latter, for the firing of firearms ("trons").
The name "Penela" comes from the word "peñela", which means small rocky hill, a clear reference to the rock where it is located.
It has a semi-triangular structure with three access doors: the Porta da Vila, the Porta da Traição and the Porta do Relógio, or Brecha das Desaparecidas, the latter a reference to the two towers that flanked this entrance, toppled during the 1755 earthquake.