The castle´s presence evokes the exciting mixture of legend, poetry and heroism that surrounds the beginning of Portuguese history. On this Monte Largo (Broad Hill), the nucleus of the future nation of Portugal was first developed.
In circa 968, Mumadona, the countess of Galicia, ordered a castle to be built on this site, where the population could seek refuge from the constant attacks unleashed upon them by the hordes of Vikings, who arrived by sea from the north of Europe, and the Muslims, who made raids from the territories that they occupied to the south.
On taking over the governorship of the province known as Portucalense from his father-in-law, Alfonso VI of León, Count Henry ordered another larger and more solid construction to be built. This represented the beginning of the important defensive structure that we can now see today, dominated by the square keep that stands between the four towers guarding each of the four corners of the walls.
Although this is not strictly documented, it is very likely that the building that stands against the inner part of the northern wall was the residence of Count Henry and the birthplace of his son Afonso Henriques, the first king of Portugal.