WILLAMETTE STONE STATE PARK
Every bit of Oregon (and the United States, for that matter), is divided into a grid. At several places across the nation, the government established a land survey starting point (called a meridian) and drew the grid lines from there. What is the Willamette Stone? It's the starting point for all the land surveying west of the Cascade Mountains in both Oregon and Washington. It's the "zero point" for the Willamette Meridian.
After a short walk down a hill in the park, you can see, touch and read about this important marker.