▁is ▁also ▁the ▁first ▁free - standing ▁project ▁made ▁by ▁August e ▁Per ret , ▁its ▁architect . ▁ ▁The ▁tower ▁is ▁the ▁sum ▁of ▁an ▁architect ural ▁and ▁struct ural ▁thought ▁particularly ▁modern ▁and ▁exact . ▁It ▁is ▁a ▁rein for ced ▁concrete ▁structure ▁whose ▁form works ▁are ▁mod ular ▁and ▁repet itive , ▁and ▁the ▁pre fab ric ated ▁fill ings ▁are ▁re - used ▁from ▁the ▁" Not re - D ame ▁du ▁Rain cy " ▁church . ▁Despite ▁criticism ▁during ▁its ▁construction , ▁it ▁was ▁later ▁de emed ▁a ▁success ▁and ▁cost ▁half ▁as ▁much ▁as ▁the ▁other ▁edific es ▁of ▁the ▁exhibition . ▁ ▁It ▁is ▁also ▁called ▁the ▁orientation ▁tower , ▁not ▁because ▁the ▁four ▁cardinal ▁directions ▁are ▁m old ed ▁at ▁its ▁top ▁but ▁because ▁an ▁orientation ▁table ▁sought ▁by ▁the ▁Tour ing ▁club ▁de ▁France , ▁enc ir cles ▁it ▁at ▁the ▁ ▁level . ▁This ▁orientation ▁table ▁allowed ▁tour ists ▁to ▁locate ▁the ▁surrounding ▁mountains ▁with ▁the ▁pleasure ▁to ▁show ▁a ▁unique ▁pan or ama ▁on ▁the ▁Al ps ▁and ▁Gren o ble ▁because ▁its ▁height ▁is ▁about ▁the ▁same ▁as ▁the ▁three ▁to wers ▁of ▁the ▁Î le ▁Ver te ▁in ▁Gren o ble . ▁ ▁History ▁ ▁It ▁was ▁ere cted ▁from ▁ 2 0 ▁May ▁ 1 9 2 4 ▁to ▁ 4 ▁May ▁ 1 9 2 5 ▁by ▁the ▁architect ▁August e ▁Per ret ▁who ▁won ▁a ▁competition ▁spons ored ▁by ▁the ▁city ▁for ▁the ▁exhibition , ▁which ▁took