The flow over bluff bodies in tandem, side-by-side or staggered arrangements represents an importance and complex configuration that is of interest for many engineering applications such as tall buildings, adjacent skyscrapers, groups of chimney stacks, tubes bundles in heat exchangers, overhead power-line bundles, bridge piers, stays, masts, chemical reaction towers, off-shore platforms and electronic systems especially in computer equipment. For these configurations, the flow interference has an essential role for several changes in the characteristics of the flow. Thus, the dynamic interaction between the structure and the fluid is one of the most fascinating problems in engineering mechanics. Various studies including both numerical and experimental investigations have been conducted for the ?ow over two-dimensional square cylinders in different arrangements, where the effects of floor (wall) and roof (free flow) of the cylinders are not included. In reality, most of cylindrical structures such as buildings have finite height with a wall in one end and free flow in another end. This case is a type of three dimensional bodies. When an object is in the wake of another, flow properties and aerodynamic forces are affected by geometry, distance between two structures and their placement toward the flow. In this research the flow around two tandem square cylinders with limited height (same as two tandem buildings) is studied experimentally by using wind tunnel and smoke tunnel. Experiments were performed in Isfahan University of Technology labs. The aspect ratio of the models (side/height) is 7. The distance between the models is varied between 1D to 5D, where D is cylinder side, and the incidence angle is varied between zero to 45 degree. The pressure coefficients (Cp) on the models’ faces are measured via 53 sensors which are placed on theirs’ faces. In this test, the Cp is measured in different gap distances and angles of attack. The flow patterns around two cylinders are investigated by smoke visualization for different gap spacing and angles of attack. Measuring velocity field and turbulence quantities around two tandem square cylinders are carried out using hot wire anemometry for various gap distances. Results of this study show that the three-dimensional of the geometry and variations of the gap distance and angle of attack have important effects on the flow patterns and pressure and velocity quantities. Three major regimes are distinguished according to the gap spacing between cylinders, that is, the single slender-body regime, the reattach regime and co-shedding or binary vortex regime. Also it was found that the results for three dimensional cylinders differ from those are reported for two dimensional cylinders. Some similarity is observed between results of the two dimensional cylinders and those for the middle plane of three-dimensional cylinder, where the effects of the floor and roof of the models on the results of this plane are small. This study shows that the mean results are relatively independent to Reynolds numbers considered in this work. Also by increasing the distance between two cylinders, the interaction is reduced and therefore the results of the upstream cylinder is almost the same as the single cylinder. Keywords : Experimental study; two tandem three dimensional square cylinders; wind tunnel; smoke tunnel; attack angle; turbulent flow.