The last official Apple-supported operating system for the classic Mac pro 1,1 or 2,1 is OS X Lion. With some workarounds it is possible to go up to OS X El Capitan but that’s where it stops. Since El Capitan got released back in 2015, most software developers dropped support for it a while ago and as good as all popular tools and applications are no longer running on El Capitan. As a valid alternative to macOS, Windows is an option here. This post covers how to get Windows 11 on your Mac Pro 1,1 or 2,2, which will allow you to install the latest software versions and get the latest patches and updates.