I left my native United States in May of 2000 with a 90-day round-trip ticket.
I returned in May of 2011 11 years and one week later.
I had no legal right to be in any European country for more than 90 days. I had no right to stay within the European Common Area, either, for more than those 90 days. But I arrived at a time when the borders were opened but the union was not quite federated, so my movement (and non-movement) on the Continent was untracked and unimpeded.
It was a different story in Ireland, which (along with the UK) is outside of the Schengen area of open borders. But, in Ireland, it was a different story indeed. The country was better to me than any place has ever been.