The wake generated by an incompressible, laminar flow past a two-dimensional circular cylinder was numerically simulated. The Reynolds number based on the cylinder diameter was 100. The instantaneous streamwise and lateral velocity fields from the wake region were obtained and subjected to Spectral Proper Orthogonal Decomposition (SPOD) so that the dominant spatio-temporal coherent structures could be identified. Based on the variation of lift with time, the Strouhal number (Str) corresponding to the vortex-shedding behind the cylinder was found to be 0.16. The same was also observed from the modal energy spectra that was obtained through the SPOD of both velocity fields. Moreover, about 99% of the modal energy at this frequency was concentrated only on the first SPOD modes of the streamwise and lateral velocity fields. When plotted to study the coherent structures, the first mode from the streamwise velocity data revealed anti-symmetrical patterns that represented the advection of coherent structures in the downstream direction. On the other hand, the first mode from the lateral velocity data contained alternating patches along the streamwise direction indicating that the vortices originating from the top and bottom of the cylinder were switching between moving closer and farther from each other.