Denis, the sixth king of Portugal (1279-1325), was the first Portuguese monarch to be born in the city of Lisbon, on 9 October, 1261.
From an early age he was readied to govern the kingdom of Portugal, which had already extended to its natural border in the Algarve.
Upon acceding to the throne, he instigated several commissions to strengthen royal power and concluded various concordats with the Holy See to normalise relations with the Church.
He was notable for his patronage of the arts and literature and wrote more than a hundred troubadour compositions (songs). He also made Galician-Portuguese the official language in the charters of the chancellery and established the country’s first university in Lisbon (1290).
He signed the treaty of Alcanizes with Castile (1297), which established a definitive border between the two kingdoms – the oldest and most stable in Europe.
He was also responsible for the reorganisation of the country’s navy, having appointed the Genoese Manuel Pessanha as admiral of Portugal in 1317.
With regard to Lisbon, he ordered the construction of a wall to defend the riverside area of the city in 1294, which became known by his name (the Dionysian Wall).
It is likely that Denis, like his father, made changes to the Castle Palace. However, the only development we can be sure of is the creation of a permanent chaplain to celebrate masses in the chapel dedicated to Saint Michael in the Royal Palace (January 10, 1299).