Discovery Day is a provincial holiday in Newfoundland and Labrador, celebrated on the Monday nearest June 24th - and this year, it's the 27th of June – today!
It is a commemoration of the discovery of the province in 1497 by John Cabot. Since 1997, it has also been known as Cabot 500 Day.
Cabot left Europe on May 20, 1497 with one ship, the Matthew. He landed on the American east coast on June 24, 1497. We do not know exactly where he landed (could have been Cape Breton, or Maine), but he went ashore, and took possession of the land. He left on or about July 20.
On his return to England, he was given a patent for a new voyage to North America the next year, and he left in 1498, this time with five ships. But he was never heard from again, and except for one of the ships, (which landed in an Irish port), the exploration was lost.
The Matthew legacy site today is tourist attraction in Bonavista, Newfoundland and Labrador. A replica was built in Bristol, UK, in 1996, and it made the journey to Bonavista in 1997.
The official website of Bonvista is http://www.bonavista.net/ourhistory.php, and the website which some of the history of John Cabot is written is http://www.win.tue.nl/~engels/discovery/cabot.html