The Fremont Bridge (Portland)

The Fremont Bridge is a bridge over the Willamette River located in Portland, Oregon. The center span was built in pieces in California, and then assembled as one piece at Swan Island, floated up river, and lifted into place over a week or so with 32 gigantic hydraulic jack-screws. The bridge was opened in November of 1973.

It was such an incredible feat of design and construction that there was actually a "visitor's center" where you could watch the action from, including a precise scale model that mirrored the lifting progress of the actual span. I used to stop by several times a week on my way home from school. Unfortunately there is no pedestrian crossing, the view is spectacular.