Château de Compiègne

Château de Compiègne (コンピエーニュ古城) is a French château, a royal residence built for.

Index Arc
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 the Louvre Museum. There is apparently at least one grimoire sealed in the château which cannot be taken away.