Mainly constructed between 1479 and 1502, Rohan Castle is characteristic of the Breton military architecture at th end of the 15th century.
The plan, an irregular quadrilateral flanked by circular towers, is one of the "philippien" type (after the King of France Philippe-Auguste, following the initiative of the construction of the Louvre fortress in Paris at the end of the 12th century). But only two towers -those of the main façade- remain here. The third one (to the north-east) was destroyed in the 19th century. As to the fourth one (to the south-east), there is still a question mark over its original existence.