The design of the towers was influenced by the work of the contemporary French architect Eugène Viollet-le-Duc, including his restorations of Carcassone and the châteaus of Aigle and Chillon. While the exterior of Castell Coch is relatively true to English 13th-century medieval design—albeit heavily influenced by the Gothic Revival movement—the inclusion of the conical roofs, which more closely resemble those of fortifications in France or Switzerland than Britain, is historically inaccurate. Although he mounted a historical defence (see box), Burges chose the roofs mainly for architectural effect, arguing that they appeared "more picturesque", and to provide additional room for accommodation in the castle.