The Citadel is a massive space station, constructed over 50 millennia ago in the heart of the Serpent Nebula, close to the star known as the Widow. The nexus of the galactic community, it acts as its political, cultural, and financial capital, housing the Citadel Council, a powerful, multi-species governing body. The Citadel is hailed as being the greatest creation of the Protheans.