It serves food (western and asian) by a rather strange self-service ticketing system, and also has a music stage.
Location: CO-EX, World Trade Center, Samseong-dong, Gangnam-gu, Seoul 135-731, Korea
(Samsung tube station). It's on the first floor, above all the shops in the (huge) centre. Information kiosks are dotted around.
Take Line 2 (green) on the underground for the Samsung station.