London: For 125 years, its guided traffic - whether on land or water - through Britain's capital.
Tower Bridge was officially opened by the Prince and Princess of Wales on June 30, 1894. It took eight years and 432 workers to construct the famous crossing.
When built, Tower Bridge was the largest "bascule" bridge ever completed - "bascule" comes from the French word for see-saw.
"The city was faced with a very specific problem," explains Chris Earlie, head of Tower Bridge.
"It had a population explosion to the east of London Bridge. So, there was way much more demand to actually cross the river and yet it needed a crossing, but it couldn't prevent the movement of trade vessels getting in and out of the Pool of London, which of course was the busiest trade port in the world.
"So, it had this really specific problem and this need for, not just a river crossing, but one that would still allow the movement of those vessels." Back in 1894, the bridge's hydraulics were powered by steam. But since 1976, they've been driven by oil and electricity. Charles Lotter has been a bridge driver at Tower Bridge for 24 years.
"So back in 1894, Tower Bridge was run by round about 80 staff, so it was quite busy, and everything was on the go, 24/7," he says.
"Because in the opening year, the first year, they did over 6,000 bridge lifts."
Nowadays Lotter and his colleagues perform about 750 bridge lifts a year, which works out at about 2 a day. Tower Bridge's high-level walkway was initially intended for the public, so people could still cross the bridge even when it was raised. But in 1910, it was closed due to lack of use… or so it was claimed, says Earlie.
"The truth was that the walkways themselves were being used by prostitutes as their offices," he says.
"And therefore the city, not wanting to police this, just shut them down to use of the general public." That decision to close the high-level walkway was reversed in 1982, when it was re-opened to the public, along with an exhibition. Now, it's home to a hair-raising glass floor walkway - 42 metres above the River Thames. It was added in 2014.
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Last year, a record-breaking 864,652 people visited the London landmark, a ten per cent increase in 2017.
"It's amazing. How buildings were built 125 years ago," says tourist Zvi Krepel. "It's a part of history, it's part of life," says tourist Jenny Escobar.
"I mean, I'm an American, but it's still part of my life, part of my history." Earlie believes the London landmark is still relevant in 2018, particularly with new, emissions regulations aimed at lessening congestion - and air pollution in the British capital. "The amount of vehicles in London at the moment means that we cannot be without a river crossing at the moment," says Earlie.
"And Tower Bridge obviously plays that really important function."
It has become such a famed symbol of the British capital, that sometimes Tower Bridge is confused with London Bridge, situated just half a kilometre upstream.
