Château de Compiègne

Château de Compiègne (コンピエーニュ古城) is a French château, a royal residence built for Louis XV. Stiyl Magnus of Necessarius mentions that Index has been to the château prior to the start of the first volume in the timeline alongside the Vatican Library, the Pataliputra ruins, Mont Saint-Michel Abbey, and Louvre Museum. There is apparently a grimoire or more sealed in the château which cannot be taken away.