(From my big trans-European trip of 1990)
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Great St Bernard pass - 2,469 m
-Finally we reached the Swiss/Italian alps.
We had driven up the Aosta valley, directly towards Europe´s highest mountain, Mont Blanc -and the Great St Bernard pass.
Instead of driving through the long tunnel lower down the mountain, we decided to take the historic road over the Great St Bernard Pass, the most ancient pass through the Western Alps. (With evidence of use as far back as the Bronze Age).
The road is only open from june to september each year.
For centuries, this was the only road between northern Europe and southern Europe for hundreds of miles on either flank. There are surviving traces of the Roman road and the "more recent" path of Napoleon's army into Italy in 1800.
http://switzerland.isyours.com/e/guide/valais/grandstbernardhistory.html