The PlaceIQ platform is a large-scale data analysis system created on the concept of location. This paper is a system overview where we provide an description of the nature of the data sources, frame of reference, abstractions, algorithmic approaches, as well as the main design tradeoffs of this system. We also provide a list of some of the lessons we learned after deploying and using this platform for numerous actual mobile advertisement campaigns. Additionally, we describe the Place Visit Rate, which is a location-based criterion for quantifying campaign response. We believe that the lift we see in Place Visit Rate in actual mobile campaigns using PIQ's audiences is a form of validation of our overall approach and provides us with guidance and feedback regarding the quality of the algorithms and audiences we create.