A MEMS structure and methods of manufacture. The method includes forming a sacrificial metal layer at a same level as a wiring layer, in a first dielectric material. The method further includes forming a metal switch at a same level as another wiring layer, in a second dielectric material. The method further includes providing at least one vent to expose the sacrificial metal layer. The method further includes removing the sacrificial metal layer to form a planar cavity, suspending the metal switch. The method further includes capping the at least one vent to hermetically seal the planar cavity.