Over the last two decades free-standing nanowire (NW) heterostructures based on III-V compound semiconductors have being attracting a steady research interest in reason of their unique potentials to the fabrication of novel and efficient nanophotonic and photovoltaic devices, and - more recently - in the field of quantum technology. A general approach to their synthesis is through application of bottom-up nanotechnology processes using well- established epitaxial growth technologies. Among the latter, metalorganic vapor phase epitaxy (MOVPE) would be the preferred one, in reason of its easy industrial scalability. Rational design of self-assembly technologies resulting in the growth of NWs with properties tuned/optimized for the specific application is still a major challenge in the field: a common difficulty to this goal is the precise correlation of the resulting nano-scale inner size/structural/ compositional properties (and their inherent fluctuations) of as-grown NW heterostructures, their resulting functional properties and employed nano-epitaxial growth conditions. This talk will present results obtained by the Lecce group on the MOVPE self-assembly of III-V core-(multi)shell NWs. Growth of both simple core-shell and core-multishell NW dense arrays will be presented, along with their resulting nano-scale structural and optical properties. In GaAs-AlGaAs core-shell NWs a strong enhancement of near band-edge GaAs optical absorption and its dependence on overgrown AlGaAs shell thickness is demonstrated, a result of improved wave-guiding of incident light into the GaAs core by the surrounding AlGaAs shell. Insertion of a few nanometers thin …