The objective of the present work is to use computational fluid dynamics (CFD) to study wind flow around a tall building with one side facing the oncoming flow at different values of Reynolds number based on building length. The method of large eddy simulation is used to model turbulence. The main task of this method is to explore and calculate directly the large-scale vortices (large eddies) by solving the filtered, time-dependent Navier-Stokes equations. The smaller, unresolved scales are modeled with Smagorinsky turbulence model. The finite volume method is used to solve the basic equations of mass and momentum conservation in the primitive form together with the turbulence model equation on a rectangular Cartesian grid of 253x184 nodal points. A smaller grid size is used near the walls of the obstacle. The results include streamlines pattern, mean velocity vector, mean velocity, pressure coefficient, and turbulent quantities. The model is verified by comparing the results for unsteady two-dimensional flow around a long square cylinder at upstream turbulence intensity 2% and length-to-width ratio 1.0 with the experimental data of previous works. Acceptable quantitative agreement between present model data and experimental results are achieved for pressure coefficient. Three different values of length-to-width ratios are used, namely 1, 2, and 3 at Reynolds number , , and respectively. The results show that the magnitude of negative pressure coefficient within the wake increases with the increase of length-to-width ratio. Different upstream turbulence intensities are used, namely 2%, 6%, 10%, 20%, and 30%. Extreme negative pressure coefficients are shown to increase with the increase of upstream turbulence intensity from 2% to 6%. The pressure distributions show no further effect for the increase of upstream turbulent intensity beyond 6%, and the flow shows turbulence level independence.