The Château de Vincennes is a massive 14th and 17th century French royal castle in the town of Vincennes, to the east of Paris, now a suburb of the metropolis. To strengthen the site the castle was greatly enlarged replacing the earlier site in the later 14th century. A donjon tower, 52 meters high, the tallest medieval fortified structure of Europe, was added by Philip VI of France, a work that was started about 1337. The grand rectangular circuit of walls, was completed by the Valois about two generations later (ca. 1410). The donjon served as a residence for the royal family, and its buildings are known to have once held the library and personal study of Charles V. Henry V of England died in the donjon of dysentery in 1422 following the siege of Meaux.
Like other more famous châteaux it had its origins in a hunting lodge, set up for Louis VII about 1150 in the forest of Vincennes. In the 13th century, Philip Augustus and Louis IX erected a more substantial manor: Louis IX is reputed to have departed from Vincennes on the crusade from which he did not return. Vincennes was more than the grim fortress: Philippe III (in 1274) and Philippe IV (in 1322) were each married there and three 14th-century kings were born at Vincennes: Louis X (1316), Philippe V (1322) and Charles IV (1328).
In the Château de Vincennes the relics of the Crown of Thorns were temporarily housed while the Sainte-Chapelle was being readied to receive them. (based on a wikipedia article / cc by-sa)