Project Monterey was an attempt to unify the fragmented Unix market of the 90s in to a single cross vendor Unix that would run on Intel Itanium (and others). The main collaborators were: IBM who brought its AIX, HP was supposed to bring some bits from HP-UX, Sequent from DYNIX/ptx and SCO from UnixWare. The project shared fate of Itanium - it totally failed. In the end Linux took its spot as a single Unix. The main legacy of Project Monterey was the famous SCO vs IBM lawsuit.
IBM did however produce AIX version for IA64 architecture! According to Wikipedia, 32 copies were sold in 2001. Except of course no one has kept a copy and the famous OS was lost forever.
Until now! This rare release has been recovered, imaged, and uploaded for posterity. It';s going to be difficult to actually run it, though, as there';s no emulator capable of running it - you';re going to need a very specific type of Itanium machine, an Intel Engineering Sample Itanium workstation, which were available from several vendors.