In this paper we illustrate the Geo Data Annotator (GDA), a framework which helps a user to build a ground-truth dataset, starting from two separate geographical datasets. GDA exploits two kinds of indices to ease the task of man- ual annotation: geographical-based and string-based. GDA provides also a mechanism to evaluate the quality of the built ground-truth dataset. This is achieved through a col- laborative platform, which allows many users to work to the same project. The quality evaluation is based on annotator agreement, which exploits the Fleiss’ kappa statistic.