A suspension bridge across the narrows of Puget Sound, connecting the Kitsap peninsula1 with the mainland of Washington State. The original bridge collapsed on November 7, 1940, just four months after it was opened to traffic.

Nearly everyone who's taken first-year college physics (and some high schoolers in advanced physics classes) has seen the famous footage of this bridge collapsing. It had already demonstrated a tendency to oscillate sinusoidally under the influence of wind gusts, an effect most disconcerting to those who traveled across it.

The wind which actually caused it to collapse, though fairly strong (around 40 mph), was hardly brutal. The collapse was brought about by the fact that the aerodynamics of the bridge structure generated vortices which rotated near or at the resonance frequency of the bridge. The resulting resonant vibration of the already-too-flexible bridge span, a bucking and twisting motion about the long axis, was caught by a movie camera, up to the bridge's spectacular demise.

After a redesign with the aid of improved aerodynamic theory, a second bridge was constructed at that point, which is still in use today.

1The original w/u, drawing from Britannica.com, named this the Olympic peninsula. I stand corrected.