The general plan is that of an irregular polygon of 9 sides – enneagon – with high curtain walls surmounted by a walkway and protected by a moat always filled with water.
The building is punctuated by strong buttresses plunging deep into the moat.
The East logis, completed in 1310, houses upstaires, a probably unique, beyond the Bourbonnais’ frontiers, ceremonial room thanks to its circular plan, its impressive size for that time and a herringbone framework forming an inverted hull.
The oldest part of the castle is the vaulted hall of the 13th century which receives a decorum probably linked to the « ‘Ordre de l’Écu D’Or' » (Order of the Golden Shield) created by Louis II in 1366 upon his return from captivity in England.
Jean de Bonnebaud, raised at the court of Moulins with the future Louis II, was one of the 19 knights.
The castle entrance gate was put up by Duke Charles Ist during the Hundred Years War and is based on the oldest masonries of the first drawbridge.
The South logis will be lifted and arranged during the Renaissance by Pierre II d’Urfé from 1444 on.
The facades, at the high court level, will be drilled for large bay windows between 1842 and 1850. The South round tower is raised during the 19th century.
The frame, however, retains considerable architectural consistency facilitating the reading of the original defensive plan.
The high court was subjected to a renovation following the original architectural layouts in order to become a service way for the noble floors.