For the sake of completeness I’ll add three images I took at the Contributor Day of WordCamp Europe 2015.
Contributors are distributed across several tables. Members of each table work together on a specific area of WordPress.
All images in this post by Florian Ziegler are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Images were taken with the Fujifilm X-T1 and the XF 14mm lens.