Château Pierrefonds is a historic castle located in the Oise department of northern France. Originally built in the 12th century, it was later transformed in the 19th century by architect Eugène Viollet-le-Duc to restore its medieval appearance. The castle features impressive towers, a large keep, and beautiful gardens, making it a popular tourist destination. The castle played a significant role in the history of France, serving as a royal residence and a military stronghold. Today, it is classified as a historical monument and attracts visitors interested in its architecture and rich history.