Namdaemun Kalguksu Alley

Category: Restaurant - Seafood Restaurant
Nearest Subway Station:  Hoehyeon (Line 4)
Distance from Subway Station: 47 meters (Exit 5)
District (gu): Jung-gu
GPS: 37.558219,126.976971 ↗
Description:

This is the other famous food street in Namdaemun and the famous dish here is kalguksu or knife cut noodles. The broth for kalguksu is usually only made with anchovies, kelp and shellfish but you should ask in case other meats are used in it. Located in a small alley very near to Exit 5 of Hoehyeon Station, the alley is filled with many stalls serving the same kalguksu menu and barley rice bibimbap (boribap). These dishes also come with a free serving of bibim naengmyeon. The price for kalguksu is only around 4,500 KRW so not only they are filling, but cheap too :)   (source 1, source 2)

Go inside that clear plastic door.

Location in Google Map:

Spicy Hairtail Fish Stew (Galchi Jorim) Alley

Category: Restaurant - Seafood Restaurant
Nearest Subway Station:  Hoehyeon (Line 4)
Distance from Subway Station:  195 meters (Exit 5)
District (gu): Jung-gu
GPS: 37.559841,126.976966 ↗ 
Description:

Tired of only eating kebab when going shopping at Namdaemun Market? How about a proper meal with spicy fish stew, rice and vegetable side dishes? Make your way to the Galchi Jorim Alley then.

This alley is one of two famous food alleys in Namdaemun. Hidden behind shop fronts, making your way to this alley is half the challenge. The other half? Enduring the spiciness of this dish and taking out the many small bones on the fish. As always check out the sources for pictures and more descriptions! (source 1, source 2)

When you've reached here, walk straight until you find many restaurants cooking their galchi jorim outside their doors.

UPDATE: I found out that alcohol may be used in the preparation of this dish from this article. Please ask first whether they used alcohol before ordering.

Location in Google Map:

Namdaemun Market

Category: Attraction - Shopping
Nearest Subway Station: Hoehyeon (Line 4)
Distance from Subway Station: 0 meter (Exit 5,6)
District (gu): Jung-gu
Description:

Namdaemun Market is a large mostly open-air market that sells a lot of things from clothes to ginseng. Many clothes sold in other places in Seoul actually come from Namdaemun. You are expected to ask for discounts and they will usually lower the original quoted price. Here is also the place to buy brooches, especially if you are going to buy them in a huge quantity to be resold back home. Souveniers like t-shirts, key chains and fridge magnets are also widely available here so this market is a convenient place for the gifts you want to buy for your family, colleagues, neighbours etc.

For Muslim travellers, there's a halal shawarma stall here. So you can stop and grab something to eat in the middle of shopping.

source: nationalgeographic.com

Location in Google Map: 

Namdaemun's Halal Shawarma

Category: Restaurant - Halal Restaurant
Nearest Subway Station:  Hoehyeon (Line 4)
Distance from Subway Station:  38 meters (Exit 6)
District (gu): Jung-gu
Description:

This is a small shop selling halal kebabs located between the exit 5 and 6 of Hoehyeon Station. It is not a restaurant and there are only two or three chairs inside the shop. Most people buy the kebabs to go. Kebabs sold are around 3,500 won per kebab. Owner displays "Halal" sign at the door.

Location in Google Map: