A novel principle of molecular architecture for monolayers containing azobenzene moieties is presented which allows the chromophores to be organized with a high density and with sufficient mobility for photochemical change. This monolayer represents a new medium for a data storage system; each single azobenzene group is in principle capable of storing the information of 1 bit. The physical properties of this monolayer have been investigated at the air-water interface. Data storage in the micrometer range is demonstrated with a single monolayer transferred on glass.