I always thought of it as fantasy but when I went to work at a library it was shelved in general fiction.  Just wanted some feedback from others.

Also I was thinking since it was the 20th anniversary of the Harry Potter series, I would like to start a re-read thread but not sure if where to put it...

Your librarian has it shelved incorrectly, but on purpose.  MOST people read general fiction and due to the popularity of Harry Potter, they just stick it where it is most likely to be noticed. My library has it in both places - general fiction for the kids and fantasy in the adult section.

Harry Potter started out to be fantasy. In fact, it was really promising. Harry fit the "hero," as explained in Joseph Campbell's The Hero With A Thpousand Faces. There was always a problem with Harry as hero, though. The hero, in historic literature dating back to Gilgamesh, must embark on a quest of great significance to his tribe. It is hard to figure out just what Harry's "tribe" was, much less the significance of his quest/adventures in this case. 

Still, it was very interesting, up to a critical point, quite skilfully written.

Then there was always the matter of the hero having to pay, more often than not with his life, to succeed in his quest. When matters come to a head, so to speak, Rowling totally finks out, not willing to face the wrath of her enormous audience that wants Harry to not only succeed but to get the girl without paying anyting personally. Boo! Hiss!

The greatest one of these stories in our lifetime, easily, is Robert Jordan's. We will never know how it would have ended. Jordan probably didn't eoither.

(and the most famous ever written, no doubt never to be approached much less surpassed. I am sure everyone has read it. The New Testament.)