See
The single most useful fact for sightseeing in Seoul is which day each palace closes. Gyeongbokgung closes on Tuesdays and Changdeokgung on Mondays; when that day is a public holiday the palace opens and closes on the next working day instead, and last entry is one hour before closing. Adult admission to Gyeongbokgung for foreign visitors aged 19 to 64 is ₩3,000, and anyone wearing hanbok gets in free, provided they wear both the jeogori top and a skirt or trousers. If you plan to see more than two palaces, the integrated palace ticket costs ₩6,000 and covers the four palaces plus Jongmyo for six months from purchase. Further out, the DMZ cannot be visited alone: foreigners join Paju City's DMZ Peace Tour from Imjingak with a passport, and the Panmunjom (JSA) tour currently accepts South Korean citizens only.