Gay neighborhoods across the United States are de-concentrating in today's so-called "post-gay" era as sexual minorities assimilate into the mainstream and disperse across the city. This context creates a problem of measurement. If by "culture" we mean to say a particular way of life of a group or subgroup of people like sexual minorities, and if that way of life is blending with other aspects of the metropolis, then how can we detect distinct urban sexual cultures? In this article, I use 125 interviews with Chicago residents to propose a two-pronged strategy. First, gay neighborhoods continue to house anchor institutions, despite ongoing residential out-migrations. These are the primary engines of community building, and they locate the material culture of a group in a specific place. Commemorations serve as a second indicator for a culture, and they too put meanings into form. Although it is a fact of city life that all neighborhoods change, anchors and commemorations are analytic devices that scholars can use to observe urban sexual cultures. More generally, they provide a framework for how to measure the shifting geographic profile of a historically stigmatized group as it experiences positive change in public opinion.