The rapid developments in communication, informatics and nano- and bio- technologies give rise to a new difficulty: how to build a complex functioning system from a large number (say, 10^10-10^12) of smart, man-made interacting elements. Such systems are too complex for design and for blueprint construction. The challenge is to develop a new engineering methodology for the creation of such systems. Currently, despite the great progress in computational power, we have not reached even the ability to simulate the intracellular gel of a single bacterium, the simplest living organism, let alone design one. This macromolecular plexus, composed of ~10^11 interacting polymers, proteins and nucleic acid segments, each with its own internal structure, continuously re-organizes its structure and composition in response to external stimuli and according to information stored in the DNA. Nature has not built such gels, cells, organs and organisms following some pre-designed blueprint, but rather via a process of biotic self-organization. I have conducted in parallel investigations of bacterial and neuronal self organization, seeking to unravel the general principles of biotic self-organization. This 9 endeavor proved successful, and our level of understanding is now such that I feel it can hint at a new approach to building complex man-made systems. Our central nervous system is composed of 10^11-10^12 neurons with about 10^16 synaptic connections. A typical bacterial colony consists of 10^9-10^12 bacteria. Both systems are not created by pre-design or according to a plan, but through a process of biotic self organization. The elements (neurons or bacteria) do not store the information required to construct the system, but rather the information for creating the needed "tools"and the guiding principles. Additional information is cooperatively generated as the organization proceeds following external stimulation. The key principles that enable it are communication and self-plasticity of the components. The outcome is an adaptable complex system that can perform many tasks, learn and change itself accordingly. Consequently, the idea of engineered self-organization is to let many collections of element self-organize in a pre-engineered environment they can exchange information with. The most efficient collections will be let to further self-improve via genetic algorithms of the components internal structure and capabilities (the analog of evolution of the potential for gene expression). The system itself should regulate the evolution of its components. I'll conclude with projections in regards to turning the conceptual idea, of engineered self-organization of communicating elements with self-plasticity, into an operational approach that will enable the creation systems too complex for design, yet with desired pre-specified capabilities.