The Castle of Siba (Persian: قلعه سیبه ), Siba castle is one of the most remarkable examples of fortified structures surrounded by trench in Kukherd District, Hormozgan province in south Iran.

The history of Siba castle goes back to the Sassanid era (226–651 CE).

It acted as fortified military base for some time and was surrounded by a huge trench for protection.

A trench was an ancient defensive strategic feature to defend the cities, castles and the forts in Persia before Islamic era.

This gigantic structure was considered a traditional defensive ancient landmark like other landmarks at that time such as huge city gates, cellars, security tunnels and underground military storages.