From 2006 - 2014 and 2016 - 2018, the research team I was part of developed operation plans for the great Islamic pilgrimage towards Mecca. These plans were mathematically optimized for crowd safety and applied by the Hajj authorities. With more than two million pilgrims currently the Hajj is one of the largest mega-events on the planet. The Hajj season 2018 was our final contribution to the safety concept of Hajj. Specifically, we are not part of any preparation activities for Hajj 2019 and have no plans to be involved in Hajj planning going forward. In 2019 the central rituals start on Friday, August 9 and end on Wednesday, August 14. I briefly summarize the project and provide references and material.