Columbia River Bonneville Dam
If you have a personal goal to visit National Historic Landmarks, then Bonneville Lock and Dam spanning the Columbia River, should be high on your list. Built in 1934, with the distinction of having the largest single-lift lock in the world in 1938, Bonneville Dam's primary purpose is to generate electricity.
Although you can't walk all the way across the Columbia River on this dam, there are great fish viewing windows and visitors' centers on both the Washington and Oregon sides and the fish hatchery and dam are open year-round. If you want to get the best fish viewing you will want to visit the fish ladders on the Washington side where more salmon and steelhead prefer to travel. You also can't miss the sea lions, attracted to this easy food source, lounging around the base of the dam. It really is an amazing destination, especially between April and September when large concentrations of fish are heading upstream.
Things to do in Portland