Tabas-E Mesina Castle in South Khorasan Province, Iran, is a mountain fortress believed to have been built during the pre-Islamic era, possibly by the Parthian Empire due to its circular design and the presence of ancient mounds nearby. The castle is strategically located on a gentle slope with mountains surrounding three sides, leaving only the southern side open to the Tabas plain.

It features a large size compared to similar forts in the region and includes several water reservoirs inside. The fortress was likely used for defense and water storage, showcasing well-adapted architecture for the area's hot and dry climate. The site remains an important historical monument reflecting ancient military and architectural ingenuity.