The neocortex is essentially multisensory, integrating information from multiple sensory modalities at all levels of processing. Traditional models of the sensory brain have emphasized unisensory processing, but recent evidence shows that multisensory integration occurs even in primary sensory areas. This article reviews multisensory processing in higher-order association cortices and discusses recent findings in unimodal sensory areas, highlighting the pervasive influence of multisensory interactions on cortical processing. The multisensory nature of the neocortex challenges the notion that senses operate independently during real-world cognition. Key multisensory regions include the superior temporal sulcus (STS), intraparietal sulcus (IPS), and frontal cortex. Neurons in these areas respond to multiple sensory inputs, showing integration of visual, auditory, and somatosensory signals. Studies in monkeys and humans demonstrate that multisensory integration occurs in primary sensory areas, such as auditory and visual cortices, where non-auditory inputs can influence auditory processing. For example, somatosensory inputs to auditory cortex are present and can modulate auditory responses. Similarly, visual inputs to the auditory cortex can influence auditory processing, and multisensory integration is observed in visual cortex, where auditory and somatosensory inputs converge. Multisensory integration is also evident in the ventral intraparietal area (VIP), where neurons respond to visual, auditory, somatosensory, and vestibular stimuli. The temporo-parietal junction (Tpt) contains multimodal representations of space, suggesting a role in orienting the head in space. In the prefrontal and premotor cortices, multisensory neurons are involved in tasks requiring integration of visual, auditory, and somatosensory information. Studies in cats and monkeys show that multisensory interactions occur in lower-level sensory areas, such as the auditory and visual cortices, and that these interactions are crucial for orienting behavior. The neocortex, including primary sensory areas, is not unimodal but rather integrates information from multiple modalities. This challenges the traditional view of unimodal processing and suggests that the neocortex is fundamentally multisensory. The integration of multisensory information is essential for perception and cognition, and the neurobiological data support the idea that the neocortex is inherently multisensory. This perspective has implications for understanding cognitive development, social cognition, and the organization of the brain.The neocortex is essentially multisensory, integrating information from multiple sensory modalities at all levels of processing. Traditional models of the sensory brain have emphasized unisensory processing, but recent evidence shows that multisensory integration occurs even in primary sensory areas. This article reviews multisensory processing in higher-order association cortices and discusses recent findings in unimodal sensory areas, highlighting the pervasive influence of multisensory interactions on cortical processing. The multisensory nature of the neocortex challenges the notion that senses operate independently during real-world cognition. Key multisensory regions include the superior temporal sulcus (STS), intraparietal sulcus (IPS), and frontal cortex. Neurons in these areas respond to multiple sensory inputs, showing integration of visual, auditory, and somatosensory signals. Studies in monkeys and humans demonstrate that multisensory integration occurs in primary sensory areas, such as auditory and visual cortices, where non-auditory inputs can influence auditory processing. For example, somatosensory inputs to auditory cortex are present and can modulate auditory responses. Similarly, visual inputs to the auditory cortex can influence auditory processing, and multisensory integration is observed in visual cortex, where auditory and somatosensory inputs converge. Multisensory integration is also evident in the ventral intraparietal area (VIP), where neurons respond to visual, auditory, somatosensory, and vestibular stimuli. The temporo-parietal junction (Tpt) contains multimodal representations of space, suggesting a role in orienting the head in space. In the prefrontal and premotor cortices, multisensory neurons are involved in tasks requiring integration of visual, auditory, and somatosensory information. Studies in cats and monkeys show that multisensory interactions occur in lower-level sensory areas, such as the auditory and visual cortices, and that these interactions are crucial for orienting behavior. The neocortex, including primary sensory areas, is not unimodal but rather integrates information from multiple modalities. This challenges the traditional view of unimodal processing and suggests that the neocortex is fundamentally multisensory. The integration of multisensory information is essential for perception and cognition, and the neurobiological data support the idea that the neocortex is inherently multisensory. This perspective has implications for understanding cognitive development, social cognition, and the organization of the brain.