Nanoelectronics research has primarily focused on devices. By contrast, not much has been published on innovations at higher layers: we know little about how to construct circuits or architectures out of such devices. In this paper, we focus on the currently most promising nanodevice technologies, such as arrays of semiconductor nanowires (NWs) and arrays of crossed carbon nanotubes (CNTs). In contrast to general-purpose programmable fabrics (such as PLAs), we investigate nano-fabrics that, while also programmable and hierarchical, are more tuned towards an application domain (in this sense they resemble ASIC). Our goal is to achieve denser designs with better fabric utilization, efficient cascading of circuits, and routing of signals. We demonstrate detailed designs of several circuits and processor data-paths, and highlight associated challenges and opportunities for optimization. Categories and Subject Descriptors C.5.3 [Computer Systems Organization]: Computer System Implementatio...