[5] A Special Bridge or Subway Committee chaired by Sir Albert Joseph Altman was formed in December 1875 to find a solution.

[7] More than fifty designs were submitted, including one from civil engineer Sir Joseph Bazalgette, which was rejected because of a lack of sufficient headroom.

Key stipulations were: Barry later noted that "at one time it was intended that the new works should be made suitable for the mounting of guns and for military occupation."

The extent of the maritime trade conducted at this time between the site of Tower Bridge and London Bridge (a distance of approximately 0.5 miles) is demonstrated in Schedule B of the Act which lists 11 active docks, quays and wharfs operating on the north side of the Thames, and 20 wharfs operating on the south side.

On 12 August 1889 the Corporation of London (Tower Bridge) Act 1889 received royal assent to extend the time allowed for construction by a further four years to 1893 and make various adjustments to neighbouring streets that had proved necessary.

[12] Construction - overseen by Edward Cruttwell - started on 22 April 1886,[7] with the foundation stone laid by the Prince of Wales on 21 June, and took eight years.

Mr (later Sir) John Jackson won three of those contracts and was responsible for the northern approach to the bridge (which started in February 1887), the foundations of the piers and the abutments of the bridge (started February 1887),[16] and the cast iron parapet for the northern approach (December 1887) at a total accepted tender cost of £189,732;[17] Sir W. G. Armstrong, Mitchell, and Co. Ltd, was awarded the hydraulics contract for which they tendered £85,232 (December 1887); Mr William Webster was responsible for the southern approach[18] at £38,383 (July 1888); Sir William Arrol & Co. had the contract for the metalwork of the superstructure[19] at £337,113 (May 1889), which amounted to about 12,100 tons;[4] Messrs Perry & Co won two contracts covering the masonry superstructure (May 1889), and paving and lighting (May 1892) for a total accepted tender of £179,455.

[15] It was reported that "few [pageants] have been more brilliant or will have a more abiding and historic interest" than the opening of Tower Bridge in the history of the City of London, and it was a "semi-State" occasion.

[20] An Act of Parliament stipulated that a tug boat should be on station to assist vessels in danger when crossing the bridge, a requirement that remained in place until the 1960s.

Opened in 1870, Tower Subway was among the world's earliest underground ("tube") railways, but it closed after just three months and was reopened as a tolled pedestrian foot tunnel.

In April 1941, a parachute mine exploded close to the bridge, causing serious damage to the bascule, towers, and engine room.

The engine became redundant when the rest of the system was modernised in 1974 and was donated to the Forncett Industrial Steam Museum by the City of London Corporation.

However, the system proved unreliable, resulting in the bridge being stuck in the open or closed positions on several occasions during 2005 until its sensors were replaced.

[47][48] Before this, the bridge's colour scheme dated from 1977, when it was painted red, white, and blue for Queen Elizabeth II's Silver Jubilee.

[50] On 8 July 2012, as part of the London Olympics, the west walkway was transformed into a 200-foot-long (61 m) Live Music Sculpture by the British composer Samuel Bordoli.

[54] This was to allow structural maintenance work to take place on the timber decking, lifting mechanism and waterproofing the brick arches on the bridge's approaches.

[4] It was at this point in 1885 that John Wolfe Barry partnered with Jones and developed the concept of the "level soffit for the upper bridge" which allowed the design to proceed as it stands today.

The bascules, weighing about 1,070 tons each including ballast and paving,[4] are counterbalanced to minimise the force required and allow raising in five minutes and have an arc of rotation of 82° with the centre of the arc, or pivot point, being 13 feet 3 inches inside the face of each pier and 5 feet 7 inches beneath the surface of the roadway.

[7] The system was designed and installed by Hamilton Owen Rendel while working for Armstrong, Mitchell and Company of Newcastle upon Tyne.

[66] To maintain the integrity of the structure, the City of London Corporation has imposed a 20-mile-per-hour (32 km/h) speed restriction, and an 18-tonne (20-short-ton) weight limit on vehicles using the bridge.

[78] Benjamin Crisler, the New York Times film critic, wrote in 1938: "Three unique and valuable institutions the British have that we in America have not: Magna Carta, the Tower Bridge and Alfred Hitchcock.

"[79] Architectural historian Dan Cruickshank selected Tower Bridge as one of his four choices for the 2002 BBC television documentary series Britain's Best Buildings.

[80][81] The bridge and its surrounding landscape was depicted in an official BBC trailer for the 2021 Rugby League World Cup (in reference to London being one of the host cities).

[87] On 10 August 1912, the pioneering stunt pilot Francis McClean flew between the bascules and the high-level walkways in his Short Brothers S.33 floatplane.

Unimpressed that senior staff was not going to celebrate the RAF's 50th birthday with a flypast, the pilot flew at low altitude down the Thames without authorisation, past the Houses of Parliament, and continued towards the bridge.

[93][94] On 31 July 1973, a single-engined Beagle Pup was twice flown under the pedestrian walkway of Tower Bridge by 29-year-old stockbroker's clerk Peter Martin.

Martin, who was on bail following accusations of stock market fraud, then "buzzed" buildings in the city before flying north towards the Lake District, where he died when his aircraft crashed some two hours later.

The Thames sailing barge Gladys, on her way to a gathering at St Katharine Docks, arrived on schedule and the bridge was opened for her.

Returning from a Thames-side lunch at Le Pont de la Tour restaurant with UK Prime Minister Tony Blair, President Clinton was less punctual and arrived just as the bridge was rising.

[99] Fearing for his safety, and that of motorists should he fall, police cordoned off the area, closing the bridge and surrounding roads and causing widespread traffic congestion across the City and East London.