Mate in 4, really hard

This is a wonderful puzzle. Only one line is given in the solution here, see if you can figure out the rest.

Mate in 4
Opificius (Oswald von Krobshofer)
Schach Express 1948
Dedicated to Emil Ramin

i like this one, it's pretty interesting

Say Black plays 2 ... Bb2 or Bc3?

Geez, one comment? This puzzle deserves better than that.

makes no sense

It's simple. White to play and mate in 4 moves. Only one line of play achieves this.

I don't understand the first rook move as well as the capture with bishop, but I do understand the rest.

1 Ra1 threatens an unstopable mate after Ra5 and Rd5. So, the Rook must be captured.

2 Rh4 prepares a pin of the g pawn, so the Knight could go to f3 after white moves his Bishop.

Nice.

But why not just Be3#??

 I agree. Checkmate in one move instead of four. White goes all the round the houses by moving and loses pieces and eventually plays Be3# on move 4, which it could have done on move ONE!!!

There is no piece protection e5 allowing the king to escape.

Because Kxe5.

LOL! The "mate in one" comments are hilarious!