One of the most important locations in the story, and one that sees plenty of consequential turning points, is the fabled fortress of Isengard.

Source: https://gamerant.com/lotr-how-saruman-get-isengard/

Thankfully, the Extended Edition opens with a lengthy new sequence showing Gandalf and his companions arriving at Isengard to confront the traitorous wizard.

Source: https://www.cbr.com/lord-of-rings-extended-edition-additional-scenes/

This may be what Saruman had expected from the very beginning—that the Ents would come to Isengard and attempt gentler methods of stopping the destruction of their forests.

Source: https://screenrant.com/lotr-why-saruman-not-kill-ents-treebeard/