The question should be where ARE the first Qurans? Because it wasnt only one. People started memorizing and writing parts of Quran when Muhammed was still alive. However they combined all the parts and turned them into a manuscript then made 5 copies 19 years after He died.
So where are those 5 copies now?
1- "Topkapi Palace" in Istanbul, Turkey.
2- Medina, Saudi Arabia.
3- Tashkent, Uzbekistan (parts are taken. Only a third of The Quran still survives)
4- Sanaa, Yemen
5- Al-Hussein Mosque Cairo, Egypt