With the steadily progressing digitization of our society and the migration into urban areas, digitized and highly connected smart cities have attracted much attention from the research community due to their impact on everyday life, potential for new innovations, and ability to reduce carbon footprints. The versatile applications, which are intended to improve life in cities in various aspects, have one thing in common-they rely on widespread, reliable, and high-performing communication networks. Therefore, optical-access networks will be a crucial part of the smart cities' network infrastructure as they provide cost-effective and high-speed connectivity to antenna sites, residents, enterprises, businesses, and regional data centers in a point-to-multipoint topology. In this article, we address the overall impact of this urban transformation on such networks. We outline our vision of the future smart sustainable city, which will leverage advanced optical-access networks. Subsequently, the physical layer design of optical-access networks is analyzed in the context of point-to-multipoint network topology. This includes a 100-Gbit/s intensity-modulation and direct-detection passive optical network (PON) and a 200-Gbit/s coherent PON utilizing eight-digital subcarrier-based time- and wavelength-division multiplexing and coherent detection. We discuss artificial intelligence-based network monitoring and resource allocation. Next, we provide a techno-economical study for sustainable fiber deployment strategies. Finally, we report the results of a network demonstration for the remote assistance of a connected autonomous vehicle.