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Duchy of Castro
Ducato di Castro  (Italian)
Ducatus Castri  (Latin)
Coat of arms of Castro
Coat of arms
Motto: Castrum civitas fidelis
The Duchy of Castro in a map by Willem Blaeu, 1640.
The Duchy of Castro in a map by Willem Blaeu, 1640.
StatusVassal of the Papal States
Common languagesLatin, Italian
GovernmentNon-sovereign monarchy
• 1537–1545
Pier Luigi Farnese (first)
• 1646–1649
Ranuccio II Farnese (last)
Historical eraEarly modern era
• Created by Pope Paul III
• Disestablished. Ranuccio II is forced to cede the lands back to Pope Innocent X
Preceded by
Succeeded by
Papal States
Papal States
Today part ofItaly

The Duchy of Castro was a fiefdom in central Italy formed in 1537 from a small strip of land on what is now Lazio's border with Tuscany, centred on Castro, a fortified city on a tufa cliff overlooking the Fiora River which was its capital and ducal residence. Technically a vassal state to the Papal States, it in fact enjoyed de facto independence under the rule of the House of Farnese until 1649, when it was subsumed back into the Papal States and administered by the House of Stampa di Ferentino.[1]

The title of Duke of Castro has been held since the late 1860s by the claimant to the headship of the House of Bourbon-Two Sicilies, since the Kingdom of the Two Sicilies was annexed to the newborn Kingdom of Italy. Prince Carlo, Duke of Castro currently holds the tile.

It was created a duchy by Pope Paul III (1534–1549) in the bull Videlicet immeriti on 31 October 1537, with his son Pier Luigi Farnese and his firstborn male heirs as its dukes. It only lasted little more than 110 years and was eclipsed by the Farnese's possessions in Parma. It stretched from the Tyrrhenian Sea to the Lago di Bolsena, in the strip of land bounded by the river Marta and the river Fiora, stretching back to the Olpeta stream and the lago di Mezzano, from which the Olpeta flows. The duchy of Latera and county of Ronciglione were annexed to it.

Wars of Castro

Main article: Wars of Castro

List of Dukes of Castro


  1. ^ Lunario Romano, Palazzi Municipali del Lazio 1984