If you think Changdeokgung Palace looks suspiciously like Gyeongbokgung Palace, you’re not far wrong. Changdeokgung was basically built as a replica of Gyeongbokgung when the latter’s location was deemed to be insufficiently auspicious.
Changdeokgung, however, has an expansive “secret garden” around the back that was resplendent in fall foliage.