  Monte Carlo studies of pure glue SU(3) gauge theory using the overlap-based
topological charge operator have revealed a laminar structure in the QCD vacuum
consisting of extended, thin, coherent, locally 3-dimensional sheets of
topological charge embedded in 4D space, with opposite sign sheets interleaved.
In this talk I discuss the interpretation of these Monte Carlo results in terms
of our current theoretical understanding of theta-dependence and topological
structure in asymptotically free gauge theories.
