These portals are in the Superstition Mountains just SE of Phoenix, Arizona, where there is already considerable mystery existing surrounding those who enter the mountains to search for the Lost Dutchman's Mine but never come out. In my book, a sinister being uses two portals to create a vampire and a werewolf to kill off targeted Arizona politicians. And one of the main characters in the book uses a portal to solve the mystery.
Physicist Lisa Randall theorizes that portals to other dimensions really exist, and she is trying to find them using the world’s largest particle accelerator in Switzerland. But I'm not sure just how mysterious a portal would remain if we were able to explain it scientifically. Then, Randall might just come up with theories that are even more strange than what we have today. In Smithsonian Magazine "She thinks an extra dimension may exist close to our familiar reality, hidden except for a bizarre sapping of the strength of gravity as we see it."
LITDP says "...many are convinced that Stonehenge in Britain is really a portal to both the past and future, as further encouraged by the recent archaeological discovery of more of the structure buried underneath the visible surface." In some cases old wells abandoned are thought to be portals into the unknown. Sedona, Arizona, has four major portals that thousands of tourists visit annually. It is even believed that your house could have a portal. More on all of this later.