The Lamb

Really like this "song". It's pretty famous by choral music standards and I had to study it for ages so I could give you tons of analytical information but instead I'll tell you that it was written in 1982 by John Tavener (not to be confused with 16th century fellow choral enthusiast John Taverner) for his nephew's third birthday. The words are taken from Blake's poem of the same name.

Oh, and the opening is bitonal with the original G major melody sung against its mirror inversion in E flat major. 

Just wait for the drop though.

"The Lamb" by John Tavener