Information in the brain is encoded by large populations of neurons – neural ensembles. The place cells in the hippocampal CA1 field have become an experimental model for the study of neural ensembles of the brain due to the convenience of research. This review is devoted to the latest studies of place cells in the CA1 field. We consider the principles of encoding space by place cells, mechanisms for controlling the activity of place cells, anatomical and physiological features of place cells in different parts of the CA1 field. Key points: 1. There are rate and phase coding; 2. Dense local connections between pyramidal neurons can provide information processing; 3. Interneurons are involved in the formation of both the rate and phase code of place cells; 4. Pyramidal neurons are anatomically and functionally divided into deep and superficial; 5. Along the dorsoventral axis, the spatial and non-spatial component of information is generalized. The CA1 field has extensive capabilities for signal processing and can implement a computationally complex operation in the cognitive processes of the brain.