Lost Library of Ivan the Terrible

When Ivan III of Russia married Sophia Palaiologina, niece of Constantine XI, her uncle gifted them a library along with many other treasures. This library somehow survived the Burning of Moscow in 1493 and continued to be passed down to her son, Vasili III, and then on to her grandson, Ivan IV. During Ivan IV's reign of terror (the second half of his reign), he feared that the library was too precious a treasure and was worried it would be stolen. So he and a few men took the collection out of Moscow (what was most likely a 1-3 day horse ride) and buried the books. To ensure the location of the library would never get out, he had the men killed. Ivan IV died before the location of the library was ever revealed. We have no idea what could have been in this library or if the contents have even survived. Though some historians have speculated that Plato's Hermocrates (the final dialogue pertaining to Atlantis) could have been part of the collection, but there's no proof that this is true.