、。
A 22-story above-ground, 2-story underground office building is under construction.
Literal
Ground-above 22-stories, ground-below 2-stories [genitive-の] office-building [subject-が] in-construction is.
A construction-notice sentence. 地上 ('above ground') and 地下 ('below ground') are the standard pair for describing building stories. 階 is the counter for floors/stories — 22階 = '22 stories.' 建設中 ('in the middle of construction') uses the ~中 suffix for ongoing states. The noun phrase is structured like a compact spec sheet: [above-ground count], [below-ground count] + [building type] + [current state]. Common in real-estate listings, architecture articles, and development news.