Built environments, including specific aspects of the surroundings designed by humans, influence our daily lives and well-being. The interaction between the environment and mental state can be studied objectively using EEG to discriminate activity related to different surroundings.Three virtual reality environments were designed (1: no nature; 2-3: nature) to study 23 participants who were asked to sit still while recording their EEG signals. To identify changes in cortical activity in different environments, a two-tailed Wilcoxon rank-sum test was applied to each electrode to compare the spectral band power features.We found significant differences in the primary visual and higher-order processing areas of the sensory and association cortices among the three environments. The most significant effects were detected in the alpha and low beta bands; the non-natural environment showed a higher band power in the parietal and occipital lobes, whereas the natural environments had a higher band power in the temporal and frontal lobes, similar patterns to those found in studies investigating neutral and emotionally charged stimuli, suggesting an emotional response to the natural environments.Our results provide proof-of-concept evidence for the significant modulation of brain activity by changing specific aspects of the external environment. We propose an objective EEG measure of neural activity in specific frequency bands and cortical regions to study mental states in response to changing particular aspects of the surroundings within an emerging conceptual framework of neuroarchitecture.