Need help finding an episode of ‘80s Astro Boy

Here’s what I remember:

*Could have been a double episode (it seemed long).

*Astro Boy had to fly around to have a bunch of battles against other robots, almost as if it were a knockout challenge (one of these was on a playa o island).

*There was a scene where the classical piece ‘In the Hall of the Mountain King’ was playing as these big, red, menacing badies skated through the streets.

*In the end Astro Boy finds a lost city o something like that.

If someone can help me out with this then that would be much appreciated.

Cheers!