How was the London tower bridge built?

1. Conception and Design: The concept for a movable bridge that would allow both river traffic and taller ships unobstructed passage through London's Pool of London was first proposed by Sir William Cubitt in 1876. The Tower Bridge as we know it today was designed by Sir Horace Jones, the city architect, and Sir John Wolfe Barry, a distinguished civil engineer.

2. Building the Foundations: Construction officially commenced on June 21, 1886, with the excavation and construction of the bridge's piers. These piers were sunk deep into the riverbed using pneumatic techniques, creating large cylindrical chambers pressurized with compressed air to prevent water from flooding in during construction. Workers labored within these pressurized chambers to dig and construct the foundations for the bridge towers and the central bascule piers.

3. Tower Erection: The two towers that grace the Tower Bridge began to rise steadily as construction progressed. These imposing structures were built from Cornish granite and Portland stone, with meticulous attention to architectural details. The towers not only provide support for the bascules, but they also house various mechanisms, hydraulic machinery, and the bridge control center.

4. Suspending the Bascules: The construction of the bascule leaves, the movable sections of the bridge that allow ships to pass underneath, was an engineering feat in itself. Steel, a relatively new material at the time, was used for the bascules' construction due to its strength and malleability. These enormous steel leaves were designed to rise vertically on giant pivots, allowing vessels of various heights to navigate the River Thames.

5. Hydraulic Power: The Tower Bridge was initially powered by a sophisticated hydraulic system. Each of the bascules was powered by a system of hydraulic cylinders driven by pressurized water. These hydraulic systems were housed within the bridge's towers, and the pressure was carefully controlled to ensure smooth and precise operation of the bascules.

6. Decorative Touches: As construction neared completion, decorative Victorian Gothic features were added to enhance the bridge's aesthetic appeal. Gargoyles, turrets, walkways, and intricate stone carvings adorned the towers and bridge components.