After the birth of their eldest son and heir, the future Pedro V of Portugal, Ferdinand was proclaimed King Dom Fernando II.

However, he would assume the regency of Portugal from 1853 to 1855, during the minority of his son King Pedro V. Ferdinand was an intelligent and artistically minded man with modern and liberal ideas.

][citation needed] In 1838, he acquired the former Hieronymite monastery of Our Lady of Pena, which had been built by King Manuel I in 1511 on the top of the hill above Sintra and had been left unoccupied since 1834, when the religious orders were suppressed in Portugal.

The building work was directed by the Baron von Eschwege, a wild architectural fantasy in an eclectic style full of symbolism that could be compared with the castle Neuschwanstein of King Ludwig II of Bavaria.

The palace was built in such a way as to be visible from any point in the park, which consists of a forest and luxuriant gardens with over five hundred different species of trees originating from the four corners of the earth.

On December 12, 1885, due to double vision caused by the tumor, he tripped when going down the stairs to the foyer of the São Carlos Theater, violently hitting his head against a wall and fell into a coma, dying three days after.

In late 1861, an attack of cholera or typhoid fever struck the royal family and Ferdinand suffered the tragedy of witnessing the death of three of his five surviving sons.