Indium nitride (InN) self-assembled nanocolumns were grown on (0001) sapphire substrates using plasma-assisted molecular beam epitaxy. The growth behavior of the nanocolumns was found to be sensitive to the In/N ratio, transitioning to a two-dimensional growth mode at higher In fluxes. We characterized the structural and optical properties of the nanocolumns and compared them to those of InN films. The nanocolumns were found to have the wurtzite crystal structure. Comparing the optical properties, the photoluminescence emission from the nanocolumns was weaker in intensity and the peak was shifted to higher energy (1.11 eV) compared to the InN films (0.83 eV).