Gyeongbokgung and Changdeokgun Palace

These two palaces are definitely a must see when you visit Korea. Aside from its  beautiful structure, also it is known worldwide.

TRIVIA

Gyeongbokgung is the main palace and the biggest of all five, while Changdeokgung is a UNESCO World Heritage Site and home to the Secret Garden (Huwon).
ADDED BONUS: When you go there during the CHOSEUK holidays, you can get in for free. A win-win solution for both tourists and locals. ^ ^

Changdeokgung

Changdeokgung (Hangul, 창덕궁, 昌德宮; literally, "Prospering Virtue Palace") — also known as Changdeokgung Palace or Changdeok Palace— is set within a large park in Jongno-gu, Seoul, South Korea. It is one of the "Five Grand Palaces" built by the kings of the Joseon Dynasty (1392–1897).^[1]As it is located east of Gyeongbok Palace, Changdeokgung — along withChanggyeonggung — is also referred to as the "East Palace" (동궐, 東闕,Donggwol).
** You can see more information from 
https://en.wikipedia.org/wiki/Changdeokgung

 Bits and pieces of the place

 ** Look how grand the entrance is

 ** Look at those intricate details. Awesome indeed!

John and Belle in the house ^ ^

Gyeongbokgung Palace

Gyeongbokgung (Hangul: 경복궁; hanja: 景福宫), also known asGyeongbokgung Palace or Gyeongbok Palace, was the main royal palaceof the Joseon dynasty. Built in 1395, it is located in northern Seoul, South Korea. The largest of the Five Grand Palaces built by the Joseon dynasty, Gyeongbokgung served as the home of Kings of the Joseon dynasty, the Kings' households, as well as the government of Joseon.

More info of this place here.

https://en.wikipedia.org/wiki/Gyeongbokgung

Bits and pieces of this place

** Also, if you happen to know the schedule of the changing of guards presentation, then it will be a good experience and memory.