According to Wikipedia, Seun Sangga is:
a shopping area located between Jongno 3-ga and Toegyero 3-ga, Jongno-gu, Seoul. It was renovated in 1966, in what The Hankyoreh described in an editorial as "a symbol of the indiscriminate redevelopment that occurred during the dictatorship years"("Don't Repeat Mistake of 'Se'un Sangga'", The Hankyoreh, 2004-11-16).
Seun Sangga is picked up in this post for the translation of 세운상가 (世運商街) among others like "Sewoon Sangga, Seun Shopping Centre, Sewoon Shopping Centre, Seun Shopping Mall, Sewoon Shopping Mall, etc."(Wikipedia).
Above all, Seun Sangga is well known as a historical symbol of industrialization and modernization of Korea in terms of urban development projects in the late 1960s.
But it is also a historical site for hacker and maker culture, since it has been an electronics market to selly and buy various consumer electronics including computers, computer parts, Videos, CDs, and many other electronic things, as well as magazines, LPs, and porn stuffs.
Its heyday was in the late 1970s and 1980s when small and middle IT manufacturers and early users such as hackers and makers had gathered, and developed both Korean IT industry and digital culture based on the sub-cultures of tinkering and making, hacking or reverse engineering, and open source sharing and collective authoring. Even if it was notoriously known as the kingdom of electronic piracy, and indeed exactly because of that, this vivid technoculture have been backrock of supporting IT industrial development.
This may be a kind of East Asian-specific historical tradition of IT industry and culture which forwards their own hacker/maker culture in this region, when considering Akihabara Electric Town (秋葉原電気街 Akihabara Denki Gai) in Tokyo, Japan, and Guang Hua Digital Plaza (光華商場 or 光華數位新天地) in Taipei, Taiwan.
Seun Sangga is still alive up to now in spite of several redevelopment projects. Not coincidentally, as the first fablab in Korea, FABLAB Seoul initiated by TIDE Institute is located exactly at this make cultural historical site.