Victoria Day is a Canadian statutory holiday celebrated on the Monday preceding May 25 in every province and territory.
It honours Queen Victoria's birthday.
In Quebec this holiday is called "National Patriotes Day".
Victoria Day is also commonly referred to as the "May two-four weekend" or the "May long weekend" and it marks the unofficial start of the cottage season where cases of beer* are consumed by hard working Canadians.
That's what we heard anyway. Or maybe it's called May two-four because May 24, 1819 is Queen Victoria's birthday :-)