Built in the late 15th century, when Otranto was more populous and important than today, and not long after the Ottoman raid that resulted in the execution of hundreds for refusing Islam, the castle is a blunt and grim structure, well preserved internally and offering views from the outer walls. It is also famous from Horace Walpole's The Castle of Otranto (1764), recognised as the first Gothic novel. Ask about guided tours (adult/reduced €3/2) of the castle's underground area.