Château-Thierry Castle, locally known as Château de Château-Thierry, lies on a hill in the town with the same name in the Aisne department in the Picardy region in France.
The first fortification at this site was built around 720 by the Frankish ruler Charles Martel as a residence for the adolescent Merovingian king under his control; Thierry IV (Theodoric). The settlement and name of the town originated from this fortification.
In 1060, Hughes Lambert leveled the top of the hill. The castle of which we see the present-day ruins was founded in the 12th century by the Counts of Champagne.
Château-Thierry Castle was rebuilt between 1220 and 1230 by Theobald IV, Count of Champagne, and until 1285 fell under the Lords of Coucy. After that date the castle was part of the royal domain, and then ceded in the early 15th century to Louis I, Duke of Orléans. After his death in 1407 the castle returned to the royal domain.
During the 15th and 16th century the castle was adapted to the use of firearms. The town and castle were taken by the English in 1421 and in 1544 by Charles V, the Holy Roman Emperor.
The Duchy of Château-Thierry was later given to the Bouillon Family, who left it without proper maintenance, causing the castle to fall into ruin.
At present you can see the remains of an enclosure which was defended on the north side by a wall with 8 circular towers with arrow slits, dating back to the early 13th century, and on the south side by a wall with rectangular towers with breeches for guns. One of these towers contains a staircase leading into the gardens. There are also remnants of the gate and the Roman keep and foundations of several other buildings to be seen. The size of the enclosure is very large so this must have been a formidable castle.
At present the site of Château-Thierry Castle can be visited freely during daytime.