Palazzo Reale now opens to the public has different functions particulary being the seat of National Library of Naplesal since the 1925, and hosting also a museums inside called Appartamento Storico, that keeps the original furnishings of the noble palace. The building was began at the beginning of 1600 in obedience to Filippo III's will and later to viceré Ferdinando di Castro, count of Lemos and her wife Caterina Zunica. The construction was given to one of the most famous and popular architect of that time, Domenico Fontana. The works then proceeded under the government of Francesco di Castro, the next viceking and went on till the middle of the XVII century. During this period was built the Chaple on the eastern side and the monumental stair in the 1651.