Liked frankfurter connection. Didn't spot it. Not sure Hadrian quite fits it's group.

Good Grid.
For Info: Hadrian's Wall was built by the Roman army on the orders of the emperor Hadrian following his visit to Britain in AD 122.
Like Widger, didn't get the frankfurter connection, I wrongly assumed that European cities would be enough for a point.

Just for the record, Elton wrote Philadelphia Freedom, Springsteen wrote Streets of Philadelphia but the legend that is Neil Young wrote Philadelphia