Abstract: A system for repositioning at least one crane superposed on a tower positioned within a bay of a building structure includes a supporting structure positioned within the bay of the building structure arranged surrounding the tower having a plurality of a repositionable support braces, at least one supporting platform reversibly mounted to the tower by a plurality of support hooks, a ladder vertically suspended from the supporting platform adapted as a track and a main platform adapted to carry and reposition the tower comprises at least one first lifting means configured to reversibly extend the main platform, at least a first climbing means and a second climbing means reversibly engageable to the ladder.