Communication networks have advanced in many respects and to levels where they can provide revolutionary capabilities in every business, governmental and societal sectors. In spite of present successes and achievements, there are many remaining challenges, and emerging classes of networks including multiple levels of networks, together with new application drivers, accentuate these challenges and engender at the same time new capabilities and new requirements in engineered networks. Such characteristics include: ubiquitous interconnectedness and integration across classes of heterogeneous networks, including communication networks as part of other network systems; networks that are neither closed nor static and which exhibit dynamicity in many respects, such as in the numbers and the kind of entities in the network, the interconnectedness structure and properties, the medium in which they operate, and in the behavior of individual nodes as well as of the collective system; networks that need to be self-organizing, self configuring, synchronized, with assured communications, continuous, robust, secure and invulnerable, such as for example mobile ad-hoc networks; and SuperGrids of dynamically integrated computational, communication, and sensor- and instrumentation-resources, and moving beyond the present Internet, to InterNets or "networks of networks" of such resources. We need new paradigms for designing, building, and managing such dynamic, interactive and mutually interdependent networks. We need to develop new and more systematic fundamental ideas and new approaches; that is: the science and the engineering for understanding, building and managing or manipulating the behavior of such systems, and enabling and ensuring efficient and optimized performance, resilience and fault-tolerance, recovery, security, etc, and managing such requirements under dynamically changing conditions. The talk will address the challenges and the opportunities presented to us.