This thesis investigates the phenomenology of massive neutral spin-1 heavy resonances (Z'-bosons) and their searches at the Large Hadron Collider. In particular the focus here is on the detection of their decay into di-lepton pairs using the ATLAS and CMS detectors in their upgraded setup for the 13 TeV centre of mass energy run (Run-II). Theoretically motivated models with an extended Electro-Weak sector are introduced and taken as benchmark to test the experimental sensitivity on different observables like the differential cross section, the Forward-Backward Asymmetry and the transverse momentum distribution, and in various phenomenological scenarios, covering the cases of narrow, wide and multiple resonances. The role of PDF and statistical uncertainties on both signal and background is discussed extensively, including the contribution of photon initiated processes.