The castle is at the southwest end of via dei Tribunali, and until recently housed the Naples Hall of Justice, which has now moved to the new Civic Center, the Centro Direzionale.

The structure was built in the 12th century by William I,[1][2] the son of Roger II of Sicily, the first monarch of the Kingdom of Naples.

In the 16th century, under the Spanish viceroyship of Pedro Álvarez de Toledo, all of the city's various legal offices and departments were consolidated here and it became the Hall of Justice - known as the "Vicaria" - the basements of which served as a prison.

The Colonna della Vicaria, a simple column on a pillar, once stood in front of the entrance; it was used to disgrace and punish debtors.

At the rear exterior of the building, facing Piazza Enrico de Nicola, is the Fontana del Formiello.