I was first introduced to Johann Sebastian Bach's Third Brandenburg Concerto as a teenager while listening to Walter (Wendy) Carlos's album, Switched On Bach. I could now write about how wonderful I find this music and how it's associated in my mind with J.R.R. Tolkien's The Hobbit... but I won't. ;)
What I will write about is how the six Brandenburg Concertos were originally ignored and then lost for many years. In 1719, Bach visited Berlin as an agent of Prince Leopold of Anhalt-Cöthen, who was buying a harpsichord. While there, he met with and impressed the local military governor, Margrave Christian Ludwig of Brandenburg-Schwedt. In the hope of securing patronage from the Margrave, Bach dedicated the six concertos to him. However, the Margrave lacked the musicians to play the concertos, and the King, Frederick William I of Prussia and the Margrave's nephew, preferred George Handel's music instead. The scores remained in the Margrave's library until his death in 1734, having never been played, and were sold for the equivalent of US$22 (in 2008 money). The scores eventually found their way into the Brandenburg archives, where they weren't discovered until sometime in the nineteenth century, which is how the "Brandenburg" Concertos got their name.
The first video is of the First Movement; the second video is of the Third Movement. Both movements are Allegro. The Second Movement (Adagio) was apparently supposed to be an improvisation on a theme, and is only occasionally performed. In this case, I can't find a video of the Freiburg Baroque Orchestra playing the Second Movement.
Brandenburg Concerto #3, First Movement:
Brandenburg Concerto #3, Third Movement: