Renfrew Castle was situated at the royal burgh of Renfrew, Scotland, which is near the confluence of the River Clyde and the River Cart. The original 12th-century castle was built by Walter fitz Alan, Steward of Scotland, upon a river islet known as the King's Inch. This was replaced in the 13th century with a new castle by the road to the Clyde ferry, which became a royal castle under King Robert II.