A method of forming at least one Micro-Electro-Mechanical System (MEMS) cavity includes forming a first sacrificial cavity layer over a wiring layer and substrate. The method further includes forming an insulator layer over the first sacrificial cavity layer. The method further includes performing a reverse damascene etchback process on the insulator layer. The method further includes planarizing the insulator layer and the first sacrificial cavity layer. The method further includes venting or stripping of the first sacrificial cavity layer to a planar surface for a first cavity of the MEMS.