When visiting South Korea, if you have enough time to explore, add Gyeongju in your list.  

Here are some of my recommendations when visiting Gyeongju:

• Bulguksa Temple
• Seokguram Grotto
• Gyeongju National Museum
• Cheomseongdae Observatory
• Anapji Pond (Donggung Palace and Wolji Pond)
• Daereungwon Tomb Complex
• Yangdong Folk Village
• Woljeonggyo Bridge

* You can use my KLOOK Code: KENNETHSURATKLOOK for discounts in some of these trips

Where I stayed in Gyeongju: 

• Blueboat Hostel Gyeongju

Read more about my South Korea blog HERE

Looking for an activity to do in Gyeongju? Check out this link from Klook