TgJ Ez41:7 :וְכֵין בִמסִיבְתָא סָלְקִין מִן אַרעָיתָא לְעִלִיתָא בְאוֹרַח מְצִיעָיתָא‏ : thus they ascend from the ground floor to the upper story on the spiral staircase through the middle way
See the entire entry for ˁellī, ˁellīṯā n.f. upper story