Despite the development of novel technologies such as millimeter-wave (mmWave) communications and 5G New Radio, current cellular networks will face difficulties to serve their users in ultra-dense scenarios due to the unprecedented growth of the mobile data traffic from various emerging data services. Unmanned Aerial Vehicles (UAVs) that carry telecommunication equipment are able to enhance the wireless connectivity in such scenarios through an on-demand redistribution of the network resources. However, their progress is still hindered by three significant issues, i.e., the lack of a consistent UAV communication framework, the energy supply, and the efficient orchestration. To that end, the HERMES project proposes a holistic approach to tackle the limitations of aerial networks by employing state-of-the-art tools and a coherent research methodology. More specifically, mmWave, optical wireless, and sub-6 GHz communication technologies along with novel multiple access techniques will be investigated to define a comprehensive communication architecture. Solar-powered charging posts with wireless power transfer capabilities deployed around the serving area will be proposed and studied to encounter the energy supply issue. Also, artificial intelligence-based tools will be leveraged to provide an efficient and profitable orchestration of the UAVs by taking into account weather and user mobility patterns. In the end of the project, a proof-of-concept demonstration and a techno-economic analysis will unravel the intrinsic characteristics of aerial networks to showcase the significant advantages of the HERMES vision that will aid the fellow to network with industry and academia, and to empower him to become a research and development innovator.