The Castle, triangular with three round towers, stands on the headland area of the old town, as advanced fortification on the side most exposed to the assaults. Originally, it was surrounded by a wide and deep moat, distinguishable only on the village side. The present appearance of the building is the result of restructuring of the Aragonese period (fifteenth century), which have expanded the facility. The interior is occupied by the parade square and buildings huddled on the northern and eastern sides. The square, now a garden and outdoor theater, rests on the rock embedded in his time in the walls. On the northern side there is the "French Hall", so named in memory of the rest of the squad of the French troops during the Napoleonic period. The Agropoli Castle is related to two characters: Luisa Sanfelice, minor character in the Neapolitan revolution of 1799, which human story has inspired the novel by Alexandre Dumas (father), "The Sanfelice", and the French writer Marguerite Yourcenar, who mentioned it in the story "Anna, soror".