I've never been to Rock City, Wall Drug or the Corn Palace. I'm pretty sure those who frequent such roadside tourist traps are the same backcountry-averse sloths who drive all the way to Crater Lake, don't even bother to leave their oversized vehicles once they get there, then heave trash out their windows as they pass through the national park. And I want to avoid them.

So you can imagine my reaction when, after telling a friend I was planning to drive to Oregon's Rogue River Valley, I receive a pamphlet in the mail advertising a roadside attraction in Gold Hill. On the cover, there's a 1940s-style logo, with three white-lettered words, "THE OREGON VORTEX," ringed by a motto that could've been conceived by the guys at Altoids ("The Famous Circular Area With Its Unique Phenomena"). Inside, strict assurances, in multiple fonts, leap off the page: PAVED ROAD ALL THE WAY, and my favorite, Large Trailer/Bus TURNAROUND at Vortex.

The text itself only reinforces my suspicion that the Oregon Vortex caters to a class of outdoor enthusiast that is wholly unfamiliar with the art of self-locomotion ("THE HOUSE OF MYSTERY at THE OREGON VORTEX is easily reached, the entire trip to and from your car entails less than 200 yards of walking...").

Still, for some unknowable reason, on the other side of Medford I leave the interstate, cross the Rogue on Highway 234, bump along Sardine Creek Road for three miles, and park in front of a gift shop with a stream babbling happily right beneath it. Thankfully, there are no tour buses, only four cars besides mine.

I surrender $7.50 at the gift shop, enter the forested grounds, and attach myself to a tour, just in time to hear a spunky young guide named Bryton issue a disclaimer: Neither she nor her employer are responsible for the Phenomena within and around this House of Mystery. A Spherical Field of Force, she explains, 165 feet in diameter, half above ground, half below ground, creates the Phenomena.

For the record, the House of Mystery is a one-room assay office from a defunct gold-mining company that, sometime prior to 1930, slid down a hill and now sits slumped at an odd angle at the very heart of the Spherical Field of Force.

From the outside, the building's floor seems as gently sloped as a driveway. But once I step in and try to walk from one end of the room to the other, it feels like I'm trying to scale the sharply pitched roof of a cathedral. I look down at my feet and they're not where they usually are, which is to say, beneath me; everyone, including me, is leaning at a 45-degree angle, as though our shoes are nailed to the floor. Bryton sets a soda bottle on the floor, and it rolls uphill.

"That just ain't right," says a guy in Bermuda shorts and a T-shirt, shaking his head.



4303 Sardine Creek Road, Gold Hill (4 miles off I-5, between Medford and Grants Pass), (541) 855-1543, www.oregon

vortex.com/main.asp . Open 9 am-5:15 pm daily July-August, 9 am-4:15 pm September- October. $7.50.

Oregonians for Rationality gives the skeptics' take on the Pheno-mena; check out www.open.org/~cowanm/skeptics/ .