This wonderfully evocative Prelude in B minor, is the opening for The Cathedral by Agustin Barrios. It is a masterpiece of the classical guitar literature. Get a modern score, as Barrios intended the piece to be written, along with his original fingerings here. These go along with the series of free video lessons Rhayn has made available on Youtube.
This piece is of a moderate level, and really is worth every effort in learning to play.