Seoul

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World Comic Convention
Metro Line 3, Hagnyeoul station

Twice a month the SETIC convention center hosts Seoul's World Comic con Festival. Admission is 4,000W but the inside is rather bland unless you are extremely familiar with Japanese and Korean anime. Your best bet is to go during convention hours and mingle with the crowds of Korean teenagers in elaborate cosplay costumes dressed as their favorite anime characters. Most are excited to see foreigners and very glad to have their pictures taken. As mentioned, this convention only takes place twice a month, so check the website Korean only to make sure it will be in session while you are in Seoul.

mountains

Seoul offers many excellent opportunities for hiking. The mountains in Seoul are at most 800 m 3,000 ft, accessible by public transit and the trails range from easy to difficult.

Mount Bukhan
Offers probably the best hiking opportunities in Seoul. It is in the north of Seoul and can be extremely crowded on holidays. To visit a popular area, take line 1 to Dobongsan station.
Mount Gwanak
– Gwanak station, line 1. The sammak temple is located in.
Mount Samseong
– Close to Gwanaksan.
Mount Inwang
– Located in central Seoul.
palaces

As the ancient seat of Korea's royalty, there are no fewer than 5 major palaces in Seoul, and some are definitely worth a visit. You can pay admission fee with T-money at the entranceno additional discount applies. ISIC holder can get a discount at ticket office.

Gyeongbok-gung
경복궁,景福宮, Yulgukno subway Gyeongbokgung or Gwanghwamun. This is Seoul's grandest Joseon Dynasty-era palace and the seat of power for centuries before it was razed in 1592 by a Japanese invasion and again by the Japanese in 1910. This was the first palace used by the Joseon Dynasty. Large parts have now been restored and the vast grounds also house the Joseon Palace Museum and the Korean Folk Museum. Admission fee is ₩3,000, open 9AM-6PM open till 7PM on holidays daily except Tuesdays.
Changdeok-gung
창덕궁,昌德宮, 99 Yulgong-ro, Jongno-gu Metro Line 3, Anguk station 5 min walk or Line 1, 3, 5 Jongno-3ga Station. This palace is second only to Gyeongbok-gung the original Gyeongbok-gung was built before Changdeok-gung but wasn't used for as long a time in historical importance, this was first built in 1405 and was the seat of power between 1618 and 1896. The buildings have all been recently restored and freshly repainted, creating a dazzling but still elegant effect that got the palace listed as an UNESCO World Heritage Site. Buildings of particular note include the blue-roofed Seonjeongjeon, which was the King's office, and the Daejojeon "Great Making Hall", his bedchamber, but perhaps most famous of all is the Huwon "Secret Garden" in the back. Access to the complex is by guided tour only ₩3,000 except on Thursdays when only self-guided tours are available in summer from April to August. Korean-language tours run every half hour Japanese-language tours also available but English tours are only offered at 10:30AM and 2:30PM, and last around 60 minutes with a walking distance of about 2.5 km, including some steps and inclines for the Huwon portion the grounds are wheelchair-accessible for most parts but may have to enter certain areas in a reverse direction from the group. Closed Mondays. Mainline bus blue: 109, 151, 162, 171, 172, 272. Branch line green: no.7025.
Deoksu-gung
덕수궁,德壽宮, subway City Hall. Located in downtown Seoul across the street from City Hall, Deoksu Palace vividly contrasts to the other nearby palaces like Changdeok Palace. Built during the mid-fifteenth century, the architecture of the buildings inside are heavily influenced with Western designs. Hence, you will see a fusion of both Korean and Western architecture. Closed on Mondays. Admission: Adults 19 to 64 years old: ₩1,000 groups: ₩800, Children aged 7-18 and soldiers: ₩500 groups: ₩400, Children 6 and under, seniors 65 and over: free.
Changgyeong-gung
창경궁,昌慶宮, Subway line 4, Hyehwa Station 10 minute walk or 20 min walk from Changdeok-gung. Originally built in 1104 as a summer palace for the Kings of the Koryo Dynasty, it became one of the main palaces during the Joseon Dynasty. The palace was used as a temporary home for the King during the time Gyeongbuk Palace was being built. Unlike other palaces that has a North-South orientation, Changgyeong Palace faces East-West. Also, what is famous about this palace is the fact it connects to Jongmyo Shrine, a holy place for the Joseon Dynasty, where sacrificial rites are practiced for previous kings and queens. Closed Tuesdays. Admission: Adults 19-64: ₩1,000 groups: ₩800, Children aged 7-18: ₩500 groups: ₩400, Children 6 and under, seniors 65+: free.
Gyeonghui-gung
경희궁,慶熙宮 and Seoul History Museum 서울역사박물관, Subway line 5, Seodaemun Station, exit 4. Originally built in the 17th century, it was burnt down twice in the 19th century. It was largely destroyed by the Japanese during the colonial rule to build a school for Japanese children. It was finally restored in 1985 and opened to the public. Free admission.