  We present an update on the study of topological structure of QCD. Issues
addressed include a comparison between the plaquette and the geometric methods
of calculating the topological density. We show that the improved gauge action
based on sqrt(3) blocking transformation suppresses the formation of
topologically charged dislocations with low action. Using a cooling method we
identify the instantons' location, estimate their size and density, and
calculate the renormalization constant Z_Q for the plaquette method.
