New London Bridge
By the end of the 18th century, it was apparent that the old London Bridge — by now over 600 years old — needed to be replaced. It was narrow, decrepit and a hazard to river traffic. In 1799, a competition for designs to replace the old bridge was held, prompting the engineer Thomas Telford to propose a bridge with a single iron arch spanning 600 ft (180 m). The revolutionary nature of this design won praise but it was never used, due to uncertainty about its feasibility and the amount of land needed for its construction.
The bridge was eventually replaced by an elegant structure of five stone arches, designed by engineer John Rennie. The new bridge was built 100 feet (30 m) west (upstream) of the original site at a cost of £2,000,000 and was completed by Rennie's son (of the same name) over a seven-year period from 1824 to 1831. The old bridge continued in use as the new bridge was being built, and was demolished after the new bridge opened in 1831.
Rennie's bridge was constructed from Dartmoor granite, with a length of 928 feet (283 m) and a width of 49 feet (15 m). The official opening took place on 1 August 1831; King William IV and Queen Adelaide attended a banquet in a pavilion erected on the bridge. The recently constructed HMS Beagle was the first ship to pass under it. It was widened in 1902–4 from 52 to 65 feet (16 to 20 m) in an attempt to combat London's chronic traffic congestion. Unfortunately, this proved too much for the bridge's foundations; it was subsequently discovered that the bridge was sinking an inch every eight years. By 1924, the east side of the bridge was some three to four inches lower than the west side; it soon became apparent that the old bridge would have to be removed and replaced with a more modern one.
On 18 April 1968, Rennie's bridge was sold to the American entrepreneur Robert P. McCulloch of McCulloch Oil for the sum of $2,460,000. (It has been claimed that he was under the mistaken belief that he was buying the much more impressive Tower Bridge, which is often erroneously thought of as 'London Bridge' by tourists, though McCulloch himself strongly denied this.) The bridge was reconstructed at Lake Havasu City, Arizona, and dedicated on October 10, 1971. Not all of the bridge was transported to America, as some was kept behind in lieu of tax duties.
The version of London Bridge that was rebuilt at Lake Havasu consists of a concrete frame with stones from the old London Bridge used as cladding. The remaining stone was left at Merrivale Quarry on Dartmoor in Devon, so a large part of Rennie's bridge never left the UK. When Merrivale Quarry was abandoned and flooded in 2003, the remaining stones were auctioned off. The reconstruction of Rennie's London Bridge spans a canal that leads from Lake Havasu to Thomson Bay, and forms the centrepiece of a theme park in English style, complete with mock-Tudor shopping mall. Rennie's London Bridge has become Arizona's second-biggest tourist attraction, after the Grand Canyon.