On your drive across the state on I-90 you'll find the very obvious bridge across the Columbia River. On the east side of the bridge is a scenic pull off worth taking at the Wild Horse Monument. There is room to stretch your legs and find a good scenic view amongst the rocks if this is part of a longer road trip. If you're up for a short hill climb you can walk right up to the old rusted horse statues for a closer view.
The statues themselves were part of an art project by Chewelah sculptor David Govedare. The project began in 1989 and was supposed to be a symbolic art pice of a 38' tall metal basket tipped over by the Great Spirit Grandfather releasing the 18 wild horses. The project funding and fell short and the sculpture was never completed. So today we get a neat silhouette of 15 wild horses running the ridge line each time we drive this section of I-90.
Nearby is Wanapum Recreation Area with camping, a large swimming beach area, some short trails, and a boat launch that get's plenty of boaters on this section of the Columbia. So if you really like what you see here, stay a day or two. It's a great camp for kids and families.
So whether you're driving through or headed here to cool off in the summer now you're a little more familiar with what the heck to horses are doing on top of the hill up there.