The growth of Co on Au(111) has been investigated in situ in ultrahigh vacuum by grazing-incidence small-angle x-ray scattering (GISAXS) and grazing-incidence x-ray diffraction (GIXD). Three different growth scenarios have been investigated. (i) In the submonolayer regime, the shape, size, and spatial organization of the Co dot network have been studied, thanks to a three-dimensional mapping of the reciprocal space around the reciprocal space origin. (ii) At the coalescence of the nanostructures and beyond, it is shown by multiwavelength anomalous GISAXS and GIXD that the percolated Co thin film is made of a bidimensional network of grain boundaries. This reveals that the Co atomic diffusion at room temperature is unable to heal defects. (iii) The Co nanopillars have been grown by sequential deposition of Co and Au following the approach proposed by Fruchart et al. [Phys. Rev. Lett. 83, 2769 (1999)]; the mapping of the reciprocal space in the small-angle regime by GISAXS unambiguously proves that the nanopillars are ordered.