The earliest pipe organ originated in Greece in the third century BC. Called a hydraulis, it was powered by air compressed by water pressure.
Bellows were added to organ design by the sixth or seventh century AD.
Charlemagne was the first to request a pipe organ in his chapel in Aachen in 812, which established the organ as the premier instrument in Western European church music for many centuries.
In the 12th century, the organ began to evolve into a complex instrument capable of producing different timbres.
My favorite organ piece is the Toccata and Fugue by J.S. Bach:
And my second favorite has got to be this one: