For more than 40 years, the monolith has lurked hidden beneath the streets of Portland. It has been seen by almost no one, and is known to just as few.

But the monolith is beautiful.

In 1970, when paper company Georgia-Pacific erected the building now known as the Standard Insurance Center, it also commissioned two tremendous pieces of public art.

(Nino Ortiz)
(Nino Ortiz)

One of them you've probably seen: Located in front of the Standard Insurance entrance on Southwest 5th Avenue, The Quest is a ginormous piece of carved white marble that has been unofficially nicknamed "Saturday Night at the Y" or "Three Groins in the Fountain" because it looks a bit like a genital-free orgy conducted inside a bidet.

The other piece of art is an entrancing, undulating and mysterious 8-foot-tall piece of sculpted and reflective chrome located in a hidden underground tunnel.

Sculpted by local artist Bruce West in 1973, the untitled work is displayed inside a hall of mirrors that reflect the sculpture infinitely back and forth—a weighty monument to light and distortion.

But to find it, you have to take the elevator in the parking garage at Southwest 4th Avenue and Salmon Street. Once in the elevator, hit "C" to reach the concourse tunnel between the garage and the Standard Insurance building.

There is nothing in that tunnel except carpet and the monolith, plus the myriad reflections of the monolith bouncing among the mirrors. There will probably be no one else anywhere near, leaving the mirrors free of other reflection. As it turns out, the sculpture is all the more beautiful for being secret.