CityFlocks is a mobile system enabling visitors and new residents in a city to tap into the knowledge and experiences of local residents, so as to gather information about their new environment. Its design specifically aims to lower existing barriers of access and facilitate social navigation in urban places. This paper presents a design case study of a mobile system prototype that offers an easy way for information seeking new residents or visitors to access tacit knowledge from local people about their new community. In various user tests we evaluate two general user interaction alternatives