On October 4, 1821 John Rennie the Elder passed away. The Scottish civil engineer designed many bridges across the United Kingdom, including the famous Waterloo Bridge over London’s Thames River, which was finished in 1817. Rennie had two other London bridges – Southwark (completed in 1819) and New London Bridge (opened in 1831). After Rennie’s death, his sons took over his business, helping to complete the New London span. Incredibly, that bridge would eventually be dismantled, packed up and moved, in 1968, to Lake Havasu City in Arizona. American entrepreneur Robert P McCulloch purchased the bridge from the city of London more than 130 years after its opening.
Early bridges were very simple structures built from easily located natural resources such as wooden logs, stone and dirt. These bridges would often fail as rain, snow and ice would erode their structures over time. Bridge building techniques stagnated in Europe and Asia from the fall of the Roman Empire through the 18th century, when advances in the studies of the sciences and engineering led bridge builders to incorporate iron and eventually steel in their construction plans.
Two hundred years on from the death of John Rennie the Elder, modern bridges are usually made with the combination of concrete, irons and cables, and can be built from very small sizes to incredible lengths that span entire mountains, rough landscapes, lakes and seas. Today, China’s Danyang-Kunshan Bridge, with a length of 164 kilometers is the world’s longest bridge and at 1991 meters, Japan’s Akashi-Kaikyo bridge is the longest suspension bridge. Rennie’s New London Bridge, which has become a major tourist attraction for Lake Havasu City, has a length of 919 feet.
John Rennie’s first cast iron bridge at Boston. Lincolnshire. showing St. Botolph’s Church (Boston Stump) and the bridge across the River Witham. Engraving after a drawing by John Hassel, 1816. (Photo by: Universal History Archive/UIG) 
Arizona, Lake Havasu City, London Bridge. (Photo by: Jeff Greenberg/UIG) 
Under the Akashi-kaikyo bridge. (Photo by: HarrisDro/Loop Images/UIG) 
Tower bridge in London at sunset. (Photo by: Freelance Images/UIG) 
Aerial view Millau viaduct by architect Norman Foster. Tarn, Aveyron, France. (Photo by: Sergi Reboredo/VW Pics/UIG) 
Lupu bridge. Shanghai. China. (Photo by: TPG/UIG) 
Si o se pol or Khajoo bridge, Isfahan, Iran. (Photo by: Giovanni Mereghetti/UIG) 
Rome. Lazio. Italy. Europe. View of the Ponte Sant’Angelo and Castel Sant’Angelo. (Photo by: Rialto Bridge. Gran Canal. Venice. Veneto. Italy. Europe. (Photo by: Pino Pacifico/REDA&CO/UIG) 
Tampa Sunshine Skyway Bridge, world’s longest cable-stayed concrete bridge, Tampa Bay, Florida. (Photo by: Joe Sohm/Visions of America/UIG) 
Sydney Harbor Bridge at night, Australia.. (Photo by: Gagliardi Giovanni /REDA&CO/UIG)
Feature image: Portrait of John Rennie the Elder (1761-1821) a Scottish civil engineer who designed many bridges, canals, and docks. Dated 19th century. (Photo by: Universal History Archive/UIG)
Sources:
History of Bridges http://www.historyofbridges.com/
Road Traffic Technology https://www.roadtraffic-technology.com/features/feature-the-worlds-longest-suspension-bridges/
History https://www.history.com/news/how-london-bridge-ended-up-in-arizona by Evan Andrews
Britannica, The Editors of Encyclopaedia. “John Rennie”. Encyclopedia Britannica, 3 Jun. 2021, https://www.britannica.com/biography/John-Rennie. Accessed 27 September 2021.