As one of the world's largest and fastest underground transport systems, the Moscow metro is an extremely reliable and affordable way to get around Europe's biggest city — a single ride costs 22 rubles ($0.75) while a 60-ride card runs 865 rubles ($30). But for all its practical advantages, the metro also can be a strange, underground world of stunning architecture, acrobatic jostling for standing room in the wagons and prime people-watching. Our staff photographers have shared their favorite shots from the metro here.