John Stokes's favourite bridge in the whole of the British capital is London Bridge because of the spectacular views it offers.
Stokes, 69, works as a tour guide on an open-top double-decker bus. Yesterday he was giving his spiel to about 50 tourists on London Bridge.
"I always tell everyone to get out their cameras, get ready to take picture of the Tower Bridge all lit up. It's the most beautiful part of our tour," he said today. "But the bus was moving very slowly. We then noticed someone lying on the pavement. . . and then a little further up we saw someone else...and then someone doing CPR on a man. We were really alarmed."
As video footage and eyewitness reports emerged from the terror attack - the third in Britain in three months - it was clear that the incident was meant for all the world to see.
A white van mowed down pedestrians as it zigzagged across London Bridge, which offers what may be the best vantage point for viewing Tower Bridge, a symbol of London itself.
"I saw blinding white headlights weaving through cars and coming at us. It hit directly to the right of me," said Dan Nguyen, an American tourist who was on London Bridge.
"I looked ahead and saw there was a distance to go before the end of the bridge, so I braced myself to jump off the bridge into the river. Then I saw my girlfriend limping and sobbing so I ran back towards the scene to drag her away," he told the BBC.
At the south end of the bridge, three assailants wearing fake explosive vests leaped out of the van and began stabbing people as they plowed through a bustling restaurant area.
They tore through nearby Borough Market leaving a trail of blood in their wake. Seven people died and dozens more were injured.
Some patrons threw glasses, stools and chairs at the attackers.
Two eyewitnesses identified as Eric and Gerard told the BBC they heard the attackers shout, "This was for Allah".
Sitting south of the River Thames, the bustling London Bridge area is popular with tourists and locals who adore its nooks and crannies, its restaurants and pubs, its elegant riverside walk.
It's an area with tourist attractions like the Shard, the tallest building in the country, which towers dramatically over the scene.
Borough Market is also a big draw. During the day, it's a food lover's paradise - vendors from around the world sell dishes with enticing aromas and tourists from around the world buy them.
As the attack unfolded, confusion rippled through the neighbourhood.
"Through the window, I saw people covered in blood. One person had blood on his neck and chest, and stumbled away. Another woman was lying on the ground - I really hope she isn't among the people we're praying for today," said Richard Angell, 33, who was enjoying Middle Eastern cuisine at a nearby restaurant.
When he was able to leave the restaurant 30 minutes after, he said, he saw "wallets, high heels and blood on the ground. People had left everything behind."
"There was a lot of screaming and people ran away as helicopters circled over us," said German tourist Alex Rumpf, 60, who was staying at the Novotel Southwark hotel.
A nurse at a nearby hospital said a "vast amount" of the serious injuries were from stab wounds.
Most victims were brought to King's College and St Thomas Hospital on the south side of the river, she said. The nurse described some of the injuries as catastrophic, including one victim with a slit throat.
The incident itself was "neutralised" very quickly, according to police. Within eight minutes of receiving the first emergency call, the police had killed three suspects.
There was still a large security cordon around the area today as the police continue to piece together what happened.
But less than 24 hours after the attack, there was also a palpable sense of defiance in the London Bridge area and beyond.
Angell, who was only metres from the attackers, said he planned to go back to the restaurant where he was dining and thank the staff.
"My friends and I have already agreed that we will go back to have a beautiful meal and to double the tip. The staff thought of us and our safety," he said.
"This is our city," London Mayor Sadiq Khan said. "We will never be cowed by terrorism."
At Walthamstow Central in northeast London, passengers were greeted by a defiant message on the subway station's information board.
"London Bridge will never fall down," it read.