ATLAS public web site: evolution to Drupal 8

Four years after deployment of our public web site using the Drupal 7 content management system, the ATLAS Education and Outreach group is in the process of migrating to the new CERN Drupal 8 infrastructure. We present lessons learned from the development, usage and evolution of the original web site, and how the choice of technology helped to shape and reinforce our communication strategy. We then discuss tactics for the migration to Drupal 8, including our choice to use the CERN Override theme. This theme was developed by the CERN web team to support clients like ATLAS to develop web sites in the relatively complex and non-intuitive environment of Drupal. Furthermore, CERN has encouraged usage of this theme to mitigate support and ease future migration. We present the effects this choice has had on the design, implementation, operation and maintenance of the new site.