This movement is in sonata format and is as clearly signposted as a symphony by Haydn or Beethoven. Catch that second subject! You just want to melt. The acrid dissonance in the development section sounds a lot like Prokofiev.
Rachmaninov: Symphony #3 in A minor, Op. 44, first movement (Ashkenazy conducting the Concertgebouw of Amsterdam)
A beautiful and brilliant slow movement. The middle section takes the place of a scherzo movement.
(second movement) (Ashkenazy)
Great finale!
(third movement) (Rachmaninov conducting the Philadelphia Orchestra via RCA Victor recording, 1939)
I wonder if Rachmaninov ever saw the movie “Alexander Nevskii,” with its score by Sergei Prokofiev, and if so, I wonder what he thought of it.