Located in the heart of Rothesay, only a few minutes' walk from the ferry terminal and harbor, this castle is unusual in Scotland for its circular plan. It dates to the beginning of the 13th century, with a large moat encircling the ramparts. Interestingly, the castle plays up the connections that this part of Scotland had with Norse rulers; King Haakon IV in particular. Scandinavia's battles with the native Scots ended with Scotland's eventual victory in the 13th century. Although mostly a restored ruin, the castle has an impressive pigeon tower and chapel within the grassy courtyard. If you dare (and you're thin enough), you can descend from the Gatehouse into a small dungeon once reserved for prisoners.