This is the main gate to Changdeokgung Palace. The Palace is inscribed on UNESCO's World Heritage List and is therefore a duly protected site.
It's within walking distance from Gyeongbokgung Palace. I've been inside on previous occasions, and the Secret Garden is just lovely. Unfortunately I don't have any photos suitable for sharing on this blog, except the following.
These are some photos of the changing-of-guards ceremony reenacted for the many tourists (and locals) that flock to the Palace.
The guard changing ceremony is held twice daily, and typically lasts about 20 minutes or so.