For most cities, there is some sense of where the "city center" is. In other words, what's the one area you would go on a 5h layover in the city? You'd probably visit The Bund in Shanghai, Times Square in New York City, or the Marina Bay Sands in Singapore. Seoul, on the other hand, feels like a much more decentralized city. Let's take a look at some contenders for the "key areas" of Seoul:
Despite most people having never heard of this area, it's probably the best contender for "city center". The Jongno area roughly used to be the historic center of Seoul, and is now home to many of the key historical tourist attractions -- such as Gyeongbokgung Palace and the Bukchon Hanok Village, as well as the Cheonggye Stream, Insadong, Gwangjang traditional market, and much more.
For tourists staying only a couple of days, you'd likely spend a lot of your time in this area. It's also well-connected to other key areas of Seoul (like Myeongdong), and close to Seoul Station.
Despite having many historical attractions, the area is also a vibrant economy of amazing food, shops, experiences, museums, all frequented just as well by locals as well as tourists.
To many travelers from Asian countries (and especially travelers from mainland China), Myeongdong is instinctively the first stop when visiting Seoul. It's a vibrant neighborhood with everything from shopping to street food.
This area used to be the place for fashion, and it's still a nice place to check out if you visit. Besides shopping, there are plenty of street foods available any given day -- and since the area is mostly for tourists, it's much less of an intimidating experience than trying street food in a random part of Seoul where they don't speak English (although, of course, it also comes with a markup in price).
While certainly nice to check out, this is not usually the most common place for locals to hang out, nor, when compared to Gangnam or Hongdae, would Korean people want to live or work in Myeongdong specifically. As such, it doesn't exactly feel right to call it the "city center".
This is probably the most famous area of Seoul amongst western travelers, and I don't have to tell you why. It's home to offices of many of the largest corporations in Korea, as well as being known for some of the best food and nightlife in the city.
If you count the entire economic output of the Gangnam area, it's almost as much as the entire city of Busan (Korea's second largest city).
Gangnam boasts the highest rent levels in Korea, and is clearly one of the most desired places to live in the city.
However, it, also, does not feel right to be considered the "city center". In fact, if you make a short trip to Korea, you could have an excellent time without visiting Gangnam at all. Gangnam was one of the latest areas to be developed during the great economic development of Korea, and prior to this development there was almost nothing in the place of what is now the richest part of Seoul. As such, it's actually quite far away from the more historical center of the city, and therefore also not very close to any of the historical tourist attractions. It's certainly a very influential district, and worth exploring, but may not be as high on the list of places to go as some expect.
Hongdae (in English, the station name is "Hongik University"), and nearby areas like Sangsu and Yeonnam Dong, are the most famous nightlife areas amongst young people in Seoul. It is known for the numerous universities in the area, and has an incredibly vibrant economy of places to visit ranging from themed cafes and escape rooms, to unique bars and nightclubs. While being known as a party area, it's worth noting that almost any area in Seoul is very densely populated and therefore still has everything one could usually expect the same as everywhere else. There are grocery stores, hotels, and restaurants of all sorts, and plenty of people of all ages live in Hongdae. That's just to say it is not only a party area.
Given its reputation as a university area, it's also probably safe to say Hongdae is one of the most english-friendly areas of Seoul (only to be surpassed by Itaewon).
Any visitor to Itaewon will likely notice this area feels a bit different from the rest of Seoul. Itaewon is known as the foreigner area of Seoul, home to many families from all over the world living in Korea. It has the most international food options of the entire city, and has no shortage of western-style bars and clubs. It also has a considerable Muslim community (at least, for Korea terms). Interestingly, Itaewon is also one of the only areas in Seoul where you can consistently encounter non-Korean staff at restaurants and shops. It's a bit isolated from the rest of the city in terms of public transit, as it's only connected by line 6, but it's still very easy to get to.
These are the most common 5 areas, but the list is far from complete. We'll continue to other areas less commonly visited by tourists in Part 2, but for now I hope it's clear that there is no one answer for the "best area of Seoul". It's a decentralized city, and it's probably fair to say that falling in love with it comes from having incredible experiences all throughout, rather than visiting one specific area and being amazed. As such, I hope you take the effort to explore these areas, to see the magic behind the endless skyline of Seoul.
Continue reading in Part 2.
