—This study investigates the upstream of the juncture flows generated by the circular cross section cylindrical body mounted on a flat plate using PIV (Particle Image Velocimetry) technique. The flow structure of laminar horseshoe vortex and a topological insight into the flow pattern of the vortex system were observed. Vortex structures for ReD (Diameter Reynolds number) 1600, 2000, 2400 and 3500 are predicted and discussed in detail. Experiments were conducted to investigate the structure of steady and periodic horseshoe vortex, the effect of Diameter Reynolds number, location of horseshoe vortex core and its variation with the change in Diameter Reynolds number and the location and nature of the saddle point located most upstream of the leading edge of the cylinder. The results revealed that (a) two different flow regimes were observed corresponding to four Reynolds number ranges; (b) the upstream vortex systems approach closer to the cylinder whereas the distance of saddle point located upstream of the leading edge of the cylinder moves away from the wall when the Reynolds number increases.