This is where everyone lives in Rooftop Prince/Attic Prince (옥탑방 왕세자) (SBS, 2012).
The house does not exist anymore. It gave way to a huge apartment complex. It was located in Seoul’s Jongno District [Jongno-gu/종로구], close to the Gyeonghui Palace [경희궁].
This is the old address, which is not valid anymore:
Address: 23 Songwol 1-gil, Jongno-gu, Seoul
서울특별시 종로구 송월1길 23
Geolocation: 37.570896, 126.965257
Getting here: Seodaemun Station [서대문역], Seoul Subway Line 5, Exit 4
— submitted by Marion KDL