Library of Ivan the Terrible

The Library of Ivan the Terrible was a library hidden underneath the in Moscow, Russia. Existing well before the construction of the Bolshoi Theatre, the library was used as a repository for generations of Assassin leaders; including Ezio Auditore da Firenze, who stored the Prophet's Codex in the library. The library was most notably used by as a storage for the Byzantine artifacts he collected.

Even by 2002, two years after the Templars initiated "the Great Purge," the Assassins continued to protect the library's secrets. During their raids on Assassin hideouts, the Templars managed to find out about the library's existence and sent Daniel Cross to infiltrate the library in 2002. Using an opening mechanism hidden behind a protrait of Ivan Ivanovich in the sewers running beneath the Bolshoi Theatre, Daniel infiltrated the library and was greeted by an Assassin sentry, who assumed Daniel was his replacement. The sentry eagerly pointed Daniel to the Prophet's Codex. Daniel read out Minerva's speech to Ezio Auditore to Warren Vidic via his earpiece, took the codex with him and killed the Assassin sentry.

Reference

 * Assassin's Creed: The Chain