Café · Seongsu
Onion Seongsu
어니언 성수
Warehouse café & bakery
It predates most of the cafés that copied its look, and it still bakes well enough to be worth the visit even without the exposed-brick backdrop.
Neighborhood: Seongsu
Best for: warehouse-industrial atmosphere plus a genuinely strong bakery counter
Instagram: @cafe.onion
Address: 서울 성동구 아차산로9길 8
About: Onion Seongsu occupies a former factory building and is often credited as the café that put Seongsu-dong on the map as a destination neighborhood, well before the area filled with flagship fashion stores. The bakery counter, not just the industrial-chic interior, is the reason regulars keep returning — bread and pastries sell out on busy days.
It opens earlier than most Seongsu cafés, from 8am on weekdays and 10am on weekends, both running until 10pm — useful if you want to beat the crowds that build later in the day.