https://www.youtube.com/watch?v=Le5ZQ52Fm5c
https://youtu.be/UhqJy5lFl6o
1977- The Francis Scott Key Bridge, a steel arch-shaped continuous through truss bridge, opens in Maryland.
https://m.youtube.com/watch?v=PzXfXTeYdV4
https://youtu.be/oKPDGUqAtyU
https://youtu.be/WvljI0VIq-E
https://youtu.be/cc-CB4cmssQ
https://youtu.be/Sfx5IwsNU9o