Deck the Halls is based on an old Welsh tune, known back in the 1700s. Mozart was known to enjoy playing the song.

The words were added in America in the 1800s.

Deck the halls with boughs of holly
Fa-la-la-la-la, la-la-la-la
'Tis the season to be jolly
Fa-la-la-la-la, la-la-la-la
Don we now our gay apparel
Fa-la-la, la-la-la, la-la-la.
Troll the ancient Yule-tide carol
Fa-la-la-la-la, la-la-la-la.

See the blazing Yule before us.
Fa-la-la-la-la, la-la-la-la
Strike the harp and join the chorus.
Fa-la-la-la-la, la-la-la-la
Follow me in merry measure.
Fa-la-la-la-la, la-la-la-la
While I tell of Yule-tide treasure.
Fa-la-la-la-la, la-la-la-la

Fast away the old year passes.
Fa-la-la-la-la, la-la-la-la
Hail the new year, lads and lasses
Fa-la-la-la-la, la-la-la-la
Sing we joyous, all together.
Fa-la-la-la-la, la-la-la-la
heedless of the wind and weather.
Fa-la-la-la-la, la-la-la-la

MP3 of Deck the Halls