The Forth Bridge opened in 1890 and it is still going strong today. The bridge is, even today, regarded as an engineering marvel. It is 2.5 kilometres (1.6 mi) in length, and the double track is elevated 46 metres (151 ft) above high tide. It consists of two main spans of 521.3 metres (1,710 ft), two side spans of 207.3 metres (680 ft), and 15 approach spans of 51.2 metres (168 ft).[ Each main span comprises two 207.3 metres (680 ft) cantilever arms supporting a central 106.7 metres (350 ft) span truss. The three great four-tower cantilever structures are 100.6 metres (330 ft) tall, each 21 metres (70 ft) diameter foot resting on a separate foundation The southern group of foundations had to be constructed as caissons under compressed air, to a depth of 27 metres (90 ft). At its peak, approximately 4,600 workers were employed in its construction. Initially, it was recorded that 57 lives were lost; however, after extensive research by local historians, the figure was increased to 98. Eight men were saved by boats positioned in the river under the working areas.
Robert Adam / Canon 7d / South Queenferry, Scotland