The most common Korean word for “building” is 건물 (geonmul). There is one more word with a similar meaning — compare them below. 「building」는 한국어로 건물.
building; structure
TOPIK 1 · noun
building
TOPIK 2 · noun
Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato