The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy programme (KPGT_soliver1) designed to map a set of nested fields totalling 380 sq. deg. Fields range in size from 0.01 to 20 sq. deg., using SPIRE at 250, 350 and 500 microns. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the reprocessed optical and ultraviolet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multiwavelength understanding of galaxy formation and evolution.