024 Italy - Rome - Ostia Antica The Ostiense Museum The museum is housed on the ground floor of a building dating back to the 15th century, known as "Casone del Sale" (Big House of Salt), as it is linked to the exploitation of the nearby salt marshes by the papal government. The building features a neoclassical façade. During the sixties of the 19th century this structure was adapted by Pius IX to become a museum. Today it serves as a museum and an office space from where the excavation work are directed.