"For whoever knows him can understand that nothing was condemned by Nero unless it was something of great excellence. Thus publicly announcing himself as the first among God's chief enemies, he was led on to the slaughter of the apostles. It is, therefore, recorded that Paul was beheaded in Rome itself, and that Peter likewise was crucified under Nero."
Ref: http://www.newadvent.org/fathers/250102.htm
I found the last sentence interesting. Eusebius doesn't say Peter was crucified in Rome, only that he was crucified by Nero. He makes a clear distinction between Paul (who was crucified in Rome) and Peter (who ???). I suppose its possible Peter could have been crucified elsewhere and his body buried in the cemetary. I'll have to do more research into this.