Although it is recognized that face-to-face interactions are important for sharing interests and (new) knowledge, it remains unknown how and where students and university employees interact in academic buildings. Therefore, the aim of this study is to analyse the location choice for face-to-face interactions in an academic building, including several personal- and interaction characteristics. An Experience Sampling Method (ESM) was used to collect data on 643 face-to-face interactions during two weeks in the Flux building at Eindhoven University of Technology, the Netherlands. In general, students more often interacted in meeting rooms than teaching staff, and support staff interacted less in eat/drink areas and the hallways than other users. Unexpectedly, some of the lectures took place outside of traditional project-/lecture space. Real estate managers of university campuses could use these results to create better interactive work environments that stimulate face-to-face interactions among employees and students of different departments. : Based on longitudinal data of ftf interactions among students and employees in an academic building, results showed that ftf interaction characteristics, compared to personal characteristics, are most important for explaining the location choice of interactions. These insights could help to design academic work environments that optimize the support of interactions.