Castelluccio, Medieval castle in Pienza, Italy.

Castelluccio is a castle sitting on a hilltop near Pienza with two round defensive towers built in traditional brick. The structure displays classic features of a medieval fortress with solid walls and fortified design.

From 1320 Castelluccio belonged to the Republic of Siena within the territory of Monticchiello. Siena, worried by its position near the border with the Papal States, protected it with two round towers and a military garrison. In 1390 part of the fortress was donated to the Hospital of Santa Maria della Scala, which turned it into a fortified farm, a "Grancia", until 1787; its coat of arms is still on the facade.

The castle's name was once extended to Il Castelluccio dei Bifolchi, after its first owners. From 1390 to 1787 part of the fortress belonged to the Hospital of Santa Maria della Scala, which turned it into a fortified farm, a grancia; its coat of arms still stands on the facade. The chapel of San Bernardino da Siena, who stayed here, can still be seen inside.

The castle stands on a hill about ten kilometres from both Pienza and Chianciano Terme, so it is reached by road rather than on foot from either town. It is privately owned and the interior is not open; the two round towers and the facade bearing the Santa Maria della Scala coat of arms are seen from outside.

The castle carries the story of Countess Giulia Maria di Montefiore, who plotted a revenge scheme and was executed in the courtyard as punishment. This dark chapter became part of the place's long memory.