What does it mean to record the ancient books of the Forbidden City?

This palace is the palace of the Yuan Dynasty. It took about twenty-five years before and after the Yuan Dynasty Palace, and it took countless labors to build it. However, due to the limited level at present, it is almost impossible to fully excavate, so a relatively small ruins of the imperial city of Yuan Dynasty can only be built on the periphery of the palace wall on the west side of Cining Palace, and a relatively small museum has been opened.