This paper introduces conceptual problems that will arise in the next 10-20 years as electronic circuits reach nanometer scale, i.e. the size of molecules. Suc1.09"h circuits will be impossible to make perfectly, due to the inevitable fabrication faults in chips with an Avogadro number of components. Hence they will need to be constructed so that they are robust to faults. They will also need to be (as far as possible) reversible circuits, to avoid the heat dissipation problem if bits of information are routinely wiped out during the computational process. They will also have to be local if the switching times reach femto-seconds, which is possible now with quantum optics. This paper discusses some of the conceptual issues involved in trying to build circuits that satisfy all these criteria, i.e. that they are robust, reversible and local. We propose an evolutionary engineering based model that meets all these criteria, and provide some experimental results to justify it.