ATLAS public website: Evolution to Drupal 8

Four years after the deployment of the ATLAS public website using the Drupal 7 content management system, the ATLAS Education & Outreach group has completed its migration 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 nonintuitive environment of Drupal. Furthermore, CERN has encouraged usage of this theme to mitigate maintenance and ease future migration. We present the effects this choice has on the design, implementation, and operation of the new site.