[davidw]

I would put Italy first - I mean, Pope Gregory was born Ugo Boncompagni and he was presumably in Rome when the idea was proposed and enacted.

[digi_owl]

heh, at the time the Italy we think of didn't really exist.

https://upload.wikimedia.org/wikipedia/commons/4/46/Italy_17...

This was how it looked as late as 1796...

[davidw]

I figured they were all catholic so they'd have switched at the same time, but it looks like the Republic of Venice, at least, took a while to change to the new calendar, and March 1st "new year" celebrations are still celebrated in some areas:

https://it.wikipedia.org/wiki/More_veneto