Recent advancements in optical microscopy are challenging our understanding of the brain. In this chapter, we show the potential of optical microscopy techniques to tackle different aspects of brain structure and function, from wholebrain neuroanatomy to neural network plasticity and functionality. We will first address novel implementations of light microscopy for cellular resolution imaging of neuronal anatomy spanning the whole brain. Afterwards, we will illustrate real-time brain rewiring of single synaptic contacts visualized through two-photon microscopy in vivo. Then, the functionality of microcircuits is investigated with nonlinear microscopy combined with fluorescent indicators of neuronal activity. Nevertheless, a single technique is not enough for targeting the articulate organization of the brain; a wider view is more efficiently gained by combining complementary approaches. In the last section of this chapter, we show examples of this multiscale approach by discussing correlative imaging obtained by combining different microscopy techniques. At the end, we discuss the perspective of a wider methodological framework fusing multiple levels of brain investigation possibly leading to an omni-comprehensive view of brain machinery.