Fernando II of Aragón was born in this building in 1452. It's an impressive mansion – more so now than back then, following a major expansion around 1600 and 20th-century restoration. The rooms contain Spanish-language information panels on Fernando's highly eventful and historically significant life, plus a model of Sos village in wood and a chapel where an audiovisual on Sos' history is shown.
The palacio is also home to Sos's tourist office.