You hear the Maginot Line tossed about a lot with this title. As well as the Atlantic Wall and Gustav Line, Siegfried Line etc. All supported by the propaganda of their supposed impenetrability, but which one is (was) in fact the strongest?
The Gothic Line was a bastard by all accounts, but the more interesting thing about these later 'lines' is possibly their very existence at all. Strange artefacts of 'no retreat' orders and strategic desperation in many ways. US, Italian & German views on the Gothic Line that I'd not seen before, with a General or two.: http://www.youtube.com/watch?v=n1L6b9VKAvg http://www.youtube.com/watch?v=skXkbjdviiw