LEP is an electron-positron collider designed for 2Ã100 GeV. For an initial phase the RF power will be sufficient to produce collisions at 2 Ã 50 GeV at a luminosity of about 1.6 Ã 10-31 cm-2 s-1. The circumference of the ring is 26.7 km and will be installed 80 - 125 m underground. Electrons and positrons will first be accelerated in a linear accelerator LIL and accumulated in a new storage ring EPA. Subsequently, the existing machines, the PS and the SPS. will be used as pre-accelerators.