My favorite chess puzzle

I came across this puzzle quite some time ago and was pretty floored.  Admittedly, it is very contrived, but it is just as astounding.  The puzzle was composed by Mark Liburkin (1910-1953), and it won 1st prize in the Veehernya Moskva composition competition in 1933.  As you work through it, you will discover it has a recurring tactical theme (one that is rare in actual play).  Although it is long, the solution is unique: each of the white moves is the only move that wins (as far as I can tell). White to play and win!