Complex sentence: Together with Kayseri Kadir Has Stadium, they belong to Kayseri Kadir Has Sports Complex, one of the newest projects in Turkey having a crucial role in Turkey's organization of Fiba 2010 basketball and bid for Euro 2016 football championships.
Split into simpler sentences: Together with Kayseri Kadir Has Stadium, it is a part of the Kayseri Kadir Has Sports Complex, one of the newest sports complexes in Turkey. The arena had a crucial role in Turkey's organization of the 2010 FIBA World Championship, and bid for the 2016 Euro football championships.