Hwanghak-dong Flea Market (황학동 벼룩시장) is one of the famous market place in Seoul, South Korea.  There is shrine for Guan Yu (关羽 [GuānYǔ]) . Walking around pick-up some second-hand items will be a good experience. Korean Noodle is delicious here and Beef and Pork BBQ also. 

:) 

When you go to South Korea. 

I have a recommendation that you may try taste some menu in Sulbing. 

Sumbing or Seolbing is dessert Cafe where they sell Pat Bing Su. 

Pat Bing Su is a dessert made of fine ice, red bean and some ingredients. 

:) 

Goguan Studio is a special place where you can wear Hanbok (Korean traditional clothes), receive make-up and hair service and take pictures. Started as a Hanbok shop back in 1962. It offers a selection of 300 different Hanbok as well as hair ornaments that you can try on. There are also professional photographers and equipment on site for those of you would like to take more professional photos. Traditional tea and calligraphy experience is provided for free. They have 400sets of Hanbok for female, 100sets for male and 100sets for children, you can have a various choice. As an option, you can get matched hair up and make-up by qualified make-up artists You can take pictures as many as you want by yourself with your camera at every single shooting set. And also get photos taken by professional photographers. A lot of props such as a sword, a fan, a bag and music instrucment are prepared for you and also selfie will be offered for free. 

You may have seen Korean Sauna & Spa in the korean drama. People eat steamed egg and have some drink with it.

It is called "Jjimjilbang" offers sweating rooms/sauna, an open-air bath, a seawater bath, a salt room. and it is often used as a filming location for various Korean television broadcasts.

You can take a glance at the daily living life of local korean inside of there and take a relax with plenty of facilities in Dragon Hill Spa.

It offers very good chance to you to learn about the background of the Korean War, the progression of the war and how a truce was eventually established. Exhibits also display ammunition used by hostile and friendly forces, information and artifacts from people displaced by the war, and information on major battles. and If you visit here after DMZ tour, it will be perfect for you to understand the history of Korean War. 

Shilla duty free shop is owned by South Korea's Samsung Group, with an average daily about two thousand groups of guests
and two hundred individual customers came to Seoul Xinluo duty-free shopping,
with the same industry, Xinluo has more unique shopping
center and excellent facilities, more than 300 kinds
of brands and rich enough supply of goods.

The customers attention

Note: Please bring your passport and air ticket.(South Korea brand you can right away, other national brand you cannot get the
items right away, go to the airport and show your bill to get your items.

Duty free shop on the ground floor and the two floor.

Gimpo International Airport is the second largest airport in Korea after Incheon International Airport. It is 17 km away from the Gimpo airport
to the Seol city center.

Domestic airlines

Korean Air
Jeju Air
T'way Airlines
Korea Express Air

International Airlines
Korean Air
Shanghai Airlines
Japan Airlines
Air China
Sichuan Air

Transportation

1.buses
All exit have buses to Seoul and Inchon International Airport,
the airport bus, Gimpo city bus.Especially for the Trade Center,
the main area of Seoul can be found in the No. 8 bus in front of the 3, 4, 5, the site take, cost of 4000~ 7000 won

2.subway
Metro
The Kimpo Airport and Seoul subway 5, 9 lines, subway is the most convenient travel to Seoul,
the most economical mode of transport.

The subway 1, 2, 3, 4 lines (Seoul Metro) - the subway 5, 6, 7, 8 lines (Seoul special city railroad commune) - the Metro Line 9 (Metro 9)