777 NE Martin Luther King Jr. Blvd.

Swinging 20 feet above the lobby inside the Oregon Convention Center's north tower, the world's largest Foucault pendulum demonstrates the rotation of our planet. A 950-pound sculpture, Principia was designed by artists Kristin Jones and Andrew Ginzel to highlight perpetual forces that ordinarily go undetected by bustling conventiongoers. Its globe has completed more than 20 million swings and, as long as the electromagnet has power, should sway along for another century.