The document describes a recommendation system that clusters Foursquare users based on their check-in histories to efficiently recommend new venues. The system first receives a user's data and category preferences, then groups the user into a cluster of similar users. It then compares the top venue choices of the most similar user to recommend the top 3 unvisited venues to the input user. The system was tested on check-in data from over 1,000 Foursquare users in New York City over 10 months.