Another Moscow site.
The Library of Ivan the Terrible.
The Library at first had been the possession of the emperors of Byzantine Empire and after the fall of Constantinople it was taken to Roma and then to Moscow in a hope chest of Sophia Palaiologina, a niece of the last Byzantine emperor Constantine XI and second wife of Ivan III of Russia.
She ordered to keep the Library in the Temple of The Nativity of the Theotokos in the Kremlin after the fire in Moscow in 1470.
In Russia to the treasures of the Library were added lots of books containing unique information, for example the library of Yaroslav I the Wise is thought to be a part of the Library. The assumptions about the composition of the Library are still being made, but here is the list of possible content: works of Titus Livius, Tacitus, Suetonius, Vergil, Marcus Tullius Cicero, Aristophanes, Polybius and etc.
According to the most assumptions, the Library has books from the famous library of Alexandria and collection of ancient maps, including the empire of Genghis Khan, as well as a unique Egyptian pharaohs papyrus, clay tablets of the Mesopotamia, parchments from Phoenicia and Judea, Indian and Chinese manuscripts, the sacred texts of Zoroaster. Present value of such a collection is difficult to imagine. Anyway, we are talking about billions of dollars.
Ivan the Terrible.
The disappearance of the Library is usually referred to the period after 1571, when Ivan the Terrible "retired from the world" in the Alexandrovaskaya village. Presumably, it was concealed in a sort of an underground hiding place. The loss of the exact place can be explained by the fact that the bloodthirsty tsar had executed builders.
The possible places where the Library can be found are the Kremlin, Kolomenskoe village, Alexandrovskaya village, Vologda, and anywhere else in Russia)))