expression, na-adjective
towering; astonishingly high
Describes something so tall or high that one must look up at it; often used figuratively for impressive scale or degree.
そのビルは見上げるように高い。
That building is toweringly tall.
彼の業績は見上げるようなものだ。
His achievements are astonishingly great.
The verb meaning 'to look up at'; 見上げるよう is the adjectival phrase derived from it, meaning 'so high one must look up'.
From the verb 見上げる (to look up) + よう (appearing, seeming), literally 'appearing as if one must look up'.