One of Led Zeppelin's few instrumentals, it weighs in at only 2:05. It's named for Jimmy Page's house in the hills of Wales, which is spelled slightly differently in the liner notes of Led Zeppelin III as "Bron-Y-Aur". It is set right into the hills, and has a lovely long stone fence. The name is Welsh for "golden breast."
As for the instrumental, it's all guitar and organ. There are no drums. It is slow, but the guitar picking is complex and rhythmically tight. Evokes a haunted nostalgia, which is probably one reason Cameron Crowe used it in Almost Famous, and the first time it's ever been used in a movie. Red House Painters admit that they "ripped off the chords from Bron-Yr-Aur" in Another Song for a Blue Guitar. Great filler for the end of any burned CD, as it goes great with fast or slow songs.
If you like it, you might also enjoy Bron-Y-Aur Stomp, Black Mountain Side, and That's the Way, also by Led Zeppelin.