There is no national wonder that grants automatic victory beside the utopia project. And no that isn't a guess so don't count it.
Incorrect, there is at least one National Wonder that does so.
Since I still haven't played Gods and Kings, and I haven't even gotten all the pre Gods and Kings DLC, there may now be more than one National Wonder that does so, but I think the second hint about its original name should be more than enough to distinguish what the mystery item is.