The fortified castle of Guise, Ruined medieval castle in Guise, Aisne, France

The fortified castle of Guise stands on a rocky spur above the Oise valley in Thiérache. Its keep, curtain walls and bastions of the Charbonnière, du Moineau, de la Haute ville and de l'Alouette survive, along with the Ducale and Paris gates and the lower levels of the Governor's Palace. Jean de Renaud installed a countermine gallery that is still visible.

The castle emerged during the Middle Ages as a defensive stronghold and became the power base of the Guise family, who wielded significant influence across France. It remained a key military installation for centuries before eventually falling into decline.

The castle gave its name to the House of Guise, which acquired the county in 1510 with Claude de Lorraine; the duke François de Lorraine saved the royal armies at Saint-Quentin in 1557. Since 1952 the Club du Vieux Manoir has restored the site through youth work camps and opens it to visitors.

The site is easy to locate since the castle overlooks the town center and is reachable from several pathways. Sturdy footwear is recommended as the ground is uneven and some areas require careful navigation.

Jean de Renaud, known as Saint Remy, installed a gallery of countermines in the 16th-century bastioned enceinte; it is still visible today. The castle was used as a quarry and even a public rubbish dump after 1923, and in 1957 a 150-metre stretch of rampart judged dangerous was demolished.