The town of Penela stands beside the road that links Coimbra (Lusa Atenas) and Tomar, the town that is split by the river Nabão, and about thirty kilometres from the first. It lies on the western slope of a hill between 230 and 290 meters high, the precise spot of the Old Castle’s Keep, the emblem of the municipality’s monumental heritage.
Founded even before the nation, its first charter was granted by D. Afonso Henriques in July of 1137, making it one of the oldest municipalities in Portugal. The charter was partly granted because of Penela's huge strategic importance during the Reconquest.
Etymologically, according to the antiquarian Santa Rosa de Viterbom the name ‘Penela’ is a diminutive of Peña, Pena or penha, and in Low Latin meant ‘hill’ or ‘rock’.
If we look at studies on existing remains, it seems that the Castle of Penela was built on a Pre-Roman fort, subsequently utilised by the Romans during their conquest in the first century B.C.
The history of Penela is also linked to the successive incursions by the Vandals, destroyers of the fortress built by the Romans, the Moors, who took over the Castle of Penela in the eighth century, and the armies of Fernando Magnus (King of Leon). It subsequently came under the control of the Count D. Sesnsando, first Governor of Coimbra (after the Reconquest in 1064), who was responsible for the construction of a strong medieval castle within the Moorish fortress that was already standing there.
The charter granted by D. Afonso Henriques in 1137 gave certain privileges to its occupants, with the objective of attracting people to settle there.
The Castle of Penela stands high up on a cliff, and only Montemor-o-Velho has a larger and stronger fort, of those that remain of the Mondego defence line. Seized once again by the Moors after 1137, it was retaken for good in 1148. However, it was D. Sancho I who brought new life to the historic castle in 1187, ordering it to be repopulated. The keep was built on the orders of D. Dinis, after further repair work.
There is one episode in the long history of the municipality which clearly demonstrates the popular support on which D. João, Master of Avis relied in the 1383/1385 crisis: when the lord of Penela, D. João Afonso Telo, the Count of Viana do Alentejo, was clearly in favour of D. Beatriz, who was married to the King of Castile, the people decided to defend and support their King. They rose up in revolt, and a man called Caspirro became famous for murdering the Count. Then Penela sent its representatives to the 1385 Cortes of Coimbra of to elect the future D. João I as Master. When he bestowed gifts on his children, he created the title Duke of Coimbra for his son D. Pedro, giving Penela over to him.