On command and conquer red alert how do you get a nanotech mainframe

If you are playing as the Empire of the Rising Sun, you may get a nanotech mainframe by building a power plant, then an ore refinery, then the nanotech mainframe is ready to be built. If you are not playing as the the Empire of the Rising Sun, then you may simply build an engineer and take it.
Note: It does require a lot of power to maintain.