A place rather than a thing -- the intersection of Gales Creek Road and the surrounding blocks where, for a few weeks in early 2016, residents heard the unexplained noise that briefly made Forest Grove internationally famous. There is nothing to see at the spot itself, but the story has become a small piece of Forest Grove folklore.
The local Theatre in the Grove ran a haunted house called "Aliens in the Grove" the following Halloween, and the noise still comes up in local conversation. If you are curious, drive the intersection of Gales Creek Road and 24th Avenue and listen; the rest of the experience is up to your imagination.