Following the success of 2014, the Olympian Symposium 2015 was attended by 120 participants, 45 universities, and 25 nationalities. It covered the topic of Cosmology and the Epoch of Reionization. The public lecture was given by the Distinguished Professor and President of the Academy of Athens Dimitri Nanopoulos and it was attended by more than 500 citizens.
The event was kindly sponsored by the University College London, the Royal Astronomical Society of the United Kingdom, and Hitachi.