This paper advances an integrated framework linking contemporary cognitive neuroscience with architectural theory and practice. It argues that architecture operates as a cognitive environment, or a medium through which neural processes of sensation, perception, memory, embodiment, and affect are continuously shaped and expressed. Drawing on empirical research in sensory processing, predictive coding, spatial navigation, embodied cognition, environmental psychology, and neuroaesthetics, the paper constructs a rigorous account of how built environments influence attention, emotion, memory formation, and behavior. The analysis proceeds across several domains. It examines how multisensory integration and perceptual priors structure the legibility and comfort of spaces; how the hippocampal–entorhinal system supports wayfinding and spatial memory; how 4E cognition reframes the human–environment relationship as fundamentally interactive; and how materiality, light, acoustics, thermal conditions, and olfactory cues modulate cognitive load, stress, and restoration. Recent work in cognitive aesthetics and neurophenomenology is then brought into dialogue with architectural experience, distinguishing where empirical evidence supports design decisions and where ethical or methodological limits remain unresolved.