Location: Henneth Annûn, the Window of Sunset

They stood on a wet floor of polished stone, the doorstep, as it were, of a rough-hewn gate of rock opening dark behind them. But in front a thin veil of water was hung, so near that Frodo could have put an outstretched arm into it. It faced westward. The level shafts of the setting sun behind beat upon it, and the red light was broken into many flickering beams of ever-changing colour. It was as if they stood at the window of some elven-tower, curtained with threaded jewels of silver and gold, and ruby, sapphire, and amethyst, all kindled with an unconsuming fire. -JRR Tolkien, TTT, page 659

Henneth Annûn was a waterfall stronghold in Ithilien. After Faramir found Frodo and Sam on their way to Cirith Ungol, he brought them there. By law they should have been killed for trespassing, but as Faramir is completely amazing, he would not kill without reason, and brought them there to hear their story and judge accordingly.

Inside the waterfall was also where he refused to take the ring :)