Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Kisimul Castle is a small medieval castle located in the centre of Castlebay on Barra, an island of the Outer Hebrides, Scotland. Kisimul Castle gets its name from the Gaelic words cìs and mul meaning "The place where taxes are paid". The earliest documentary record of Kisimul Castle dates from the mid 16th century. Kisimul sits on a rocky islet in the bay just off the coast of Barra, and as it is completely surrounded by the sea; it can only be reached by boat making the fortification impregnable.