An important open question in neuroscience is how sensory information is represented and transformed by circuits in the cortex. To study this we created the Allen Brain Observatory. This open dataset is a large-scale, systematic survey of physiological activity in the awake mouse cortex recorded using 2-photon calcium imaging. It consists of over 63,000 neurons recorded in over 1300 imaging sessions, surveying 6 cortical areas, 4 cortical layers, and 14 transgenically defined cell types (Cre lines). In this talk I will describe our analysis of this dataset revealing functional organization of visual responses across cortical areas and layers. Using the joint reliabilities of responses to multiple stimuli, we classify neurons into functional classes and validate this classification with models of visual responses. Further, I will show recent work looking at how inhibitory interneurons in the cortical circuit regulate network dynamics, balancing sensitivity and network stability.