The Castle of Leontari is one of the most significant medieval fortifications of Arcadia, its surviving remains still dominating the hill above the modern settlement. Its historical importance is closely tied to the flourishing of Leontari, which reached its peak during the Byzantine period. After the destruction of nearby Veligosti—a major Frankish settlement—around 1300, Leontari developed into the administrative and commercial center of the region and gradually emerged as the second most important city of the Despotate of Mystras. Owing to its strategic position in the center of the Peloponnese, at the foothills of Mount Taygetos, the castle served as a key stronghold for controlling the hinterland. During the period of Ottoman rule, it retained its significance as a military outpost. The traveler Evliya Çelebi, who visited the Peloponnese between 1668 and 1670, records that the castle possessed a triple fortification system, with three successive enclosures and an exclusively Christian population. The outer enclosure, adapted to the natural topography, had a single gate on its southeastern side, while only scant traces survive today from the two inner enclosures. In the Second Ottoman Period, the presence of powerful Ottoman officials such as Pigli Bey and Zerdaroglou underscores the settlement’s importance as a major administrative center. The castle was reinforced once again, and its garrison was placed under the direct supervision of the Sublime Porte. The soldiers’ salaries were paid directly by the Sultan—a practice reserved only for fortresses of exceptional importance, such as Mystras, Nafplio, Patras, Methoni, Koroni, and Navarino. Although its prominence gradually declined from the late 18th century onward, when Tripoli emerged as the dominant administrative center of the region, the Castle of Leontari retains its symbolic weight as a monument of the area’s long and layered history. Today, sections of the walls, the remains of a cistern, and a few traces of the inner fortifications survive. In the surrounding area, Byzantine churches and the so‑called Kato or “Voulomeni” Fountain are also preserved.