Palazzo Cassano Ayerbo D'Aragona, Palatial residence in Salita San Raffaele, Naples, Italy.

The Palazzo Cassano Ayerbo D'Aragona is a grand residence located on Salita San Raffaele with multiple floors and detailed interior spaces. An octagonal staircase forms the architectural heart of the building, rising through several levels and framing the movement through the entire structure.

The building is recorded in Parrino's 1725 text as a hunting lodge in the Sant'Efremo Nuovo area. In 1748, Prince Giuseppe Maria d'Aragona commissioned renovation and expansion works. A 1785 restoration by architect Gaetano Barba removed many Baroque decorations, giving the palace a more classical imprint. In 1906 it was bought by the Sisters of the Addolorata, who built the church of the Addolorata in the garden.

The Fondazione Morra, active in promoting contemporary art, acquired the building and runs artist residencies and international cultural initiatives there. A small part is still occupied by the Suore dell'Addolorata, the nuns who bought the palace in 1906 and built the church of the Addolorata in its garden.

Access to the building requires climbing a steep ramp that leads to a rounded archway gate made of gray stone. Plan for this uphill walk and wear suitable footwear since the approach involves several steps.

The octagonal staircase has never been studied in architectural criticism. Its design is attributed to Ferdinando Sanfelice, who died on 1 April 1748, the year work began; the project was probably carried out by Giuseppe Astarita. The polygonal structure has a central ramp flanked by two side ramps, divided by a landing with one arched side.