Ventspils Castle () is located in Ventspils, Latvia. It is one of the oldest and most well-preserved Livonian Order castles remaining, in that it has retained its original layout since the 13th century. Through its 700 year history, it has been used as a fortress, residence, garrison, school, military base, and prison. In 1995, the castle was restored to its 19th-century appearance, and was converted into a museum.