Full-scale monitoring of structures is extremely important for better understanding their behavior under environmental loads. Structural properties, e.g., natural frequencies and damping of structures, as-built, can be determined from measured response time histories using system identification techniques. Measurements made at different amplitudes of motion also help in capturing the variations in both frequency and damping parameters with response level.  This thesis examined acceleration data from an 800-ft building in Boston to identify the in-situ dynamic properties of the structure. The frequency and damping estimates were compared using spectral and random decrement techniques. The influence of limited data available for this study and the inherent biases associated with these techniques were discussed. The close coupling of the sway and torsion modes and the manifested beating phenomenon were peculiar characteristics of this structure that add to the difficulty in the estimation of damping. This thesis also examined full-scale surface pressure data measured on this building. The data was statistically analyzed to gain better understanding of the action of wind on bluff structures with separated flow regions.