The Myst library is the central building on Myst Island. Here, Atrus stored his journals, his Linking Books, and his Descriptive Books. He also wrote a great many Ages in this library. However, the greed of his sons, Sirrus and Achenar, was the ultimate undoing of that collection. The entire bookcase was put to the torch, and only a small handful of journals and Books survived the blaze.
There is a secret back door in the library, accessible by lowering the bookcase into a set of stairs. This doorway leads to an elevator which ascends to the Tower. This elevator also went down into the island itself, to a private, personal space where Atrus and his family lived, though it cannot be accessed in any of the Myst games.
Yeesha has granted limited access to Myst's library to explorers who have completed the Path of the Shell. While the library appears to be in a state of considerable disrepair after 200 years of abandonment, it seems to have held up rather well to the tests of time.
Myst V: End of Ages appearance
In Myst V: End of Ages, the Linking Book back to Myst—which Yeesha refers to as a "cursed island"—has been locked. Esher, knowing that Yeesha and the bahro will refuse to come to the island, unlocked the Book and attempted to lure Dr. Watson/the player back to the Age. There, he had erected a crude Keep for the Tablet, in the hopes of gaining complete control over them. While the library does make an appearance in this "bad ending" of the game, it is not considered canon and should not be relied upon as an accurate representation of the library's current condition.