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The anatomical correlates of consciousness, meaning restricted to the level of alertness and explicit access to perceptual or cognitive information, involve subcortical and high-level cortical regions. Consciousness needs arousal as a prerequisite but does not include it. Several strongly interconnected nuclei of the reticular formation and the forebrain, with relays to the cortical regions, are required for normal wakefulness. Unconscious processes have been described in brain-damaged patients, at the subcortical level (in blindsight, for example) and in cases of cortical lesions (visual agnosia, neglect, visual extinction, and anosognosia), then reported in healthy subjects (using subliminal perception or the priming effect, and functional neuroimaging). A large distributed cortical network would be necessary for conscious processes, involving prefrontal, cingulate, and parietal regions. The Global Neuronal Workspace model incorporates these data and postulates strong connections between this network and multiple specialized and non-conscious processors. The role of this anatomical network in consciousness remains a matter of debate: the prefrontal cortex could be excluded from the Neuronal Correlates of Consciousness (NCC), whereas a “posterior hot zone” seems to play a predominant role in consciousness.