The Golden Gate bridge spans the Golden Gate strait, connecting the city of San Francisco to Marin County. Construction of the bridge began in 1933 and was completed in 1937 at a cost of $903 million. At the time of it's completion it was the largest suspension bridge span in the world. It remains the second largest suspension bridge span in the United States.
The Iron Bridge crosses the River Severn spanning the Ironbridge Gorge. The bridge was completed in 1779 and opened in New Year's Day 1781. The bridge was the first of its kind and because of this construction was based on carpentry methods.