Tomorrow - March 1st - many of us will don our daffodils and leeks in celebration of the Patron Saint of Wales.
However, recent figures show more than half of people in Wales don't know why St David's Day is celebrated.
The survey by Cadw also revealed other statistics about the nation's knowledge of Welsh history.
- 56% thought there were fewer than 100 castles in Wales - when in fact there are more than 600
- 45% haven't visited a castle in the last five years or more
- 70% of Welsh people don't know why Santes Dwynwen Day is celebrated on 25th January
Tomorrow, Cadw is opening 128 historic sites for free in celebration of the Patron Saint of Wales so people can explore their heritage.
Heritage Minister Huw Lewis AM says he wants everyone to realise the benefits of what's on our doorstep.
And in case you weren't sure...