Synesthesia is a fascinating phenomenon in which a particular perception induces a concurrent perception resulting in a kind of double perception. This phenomenon has received considerable attraction in the last 15 years by neuroscientists and cognitive psychologists. Here I will summarize and discuss some of the main findings and ideas from this research. First, I will discuss the main neurophysiological models trying to explain this extraordinary phenomenon. Secondly, I will describe the findings trying to delineate the time course of synesthetic perception in relation to the associated neurophysiological models. Finally, current findings reporting specific and general neuroanatomical features of the synesthete’s brain will be discussed. These findings will be integrated into the current models about the neurophysiological underpinnings of synesthesia.