Built in the 12th century by Gualdim Pais, it was the seat of the Templar Order in the country, having served as a pantheon of the Order's masters.
By Bull of Pope Callisto III, of March 13, 1455, it became a Diocese being the matrix of all the churches of the discovered territories (Azores, Madeira, India, Brazil and Africa).
Classified as a National Monument since 1910, it is one of the most emblematic examples of Gothic art in Portugal.