It is well established that matter at nanoscale exhibits several size effects governed by size, shape, surface to volume ratio as well as by the breaking of the 3-D symmetry and spatial confinement. This contribution reports on Quantum Mechanic governed phenomena at room temperature in several nanoscaled systems. Due to the relativistic contraction in connection to the Dirac dynamics of the valence electrons of Mercury, this later is shown to be solid at room temperature for Nanoparticles of mercury with size below 5 nm in Ø. Owing to their large longitudinal to transversal anisotropy ratio & their multi-electronic properties, Carbon Nanotubes are ideal nanosystems to localize light and hence to observe the Anderson Localization at room temperature [1]. Likewise, due to the wave-particle duality, it is demonstrated that cold neutron wave-matter wavepackets can be trapped in the equivalent of Nanoscaled Fabry-Perot nanoresonators