By Ian Youngs, BBC culture reporter and Bethany Bell, BBC News in Vienna
Taylor Swift fans came out in force on Vienna's streets to sing her songs and show their defiance, a day after her concerts there were cancelled because of a plot to attack them.
Hundreds of Swifties staged an impromptu open-air gathering to overcome the disappointment of not seeing the US superstar on her record-breaking Eras tour.
They also said they understood the decision to cancel the stadium shows on Thursday, Friday and Saturday, and were grateful to the police.
Austrian authorities said they had foiled a plan by a supporter of the Islamic State group to carry out a suicide attack.
One British fan called Becky said she felt "sombre but also excited by the atmosphere" on Corneliusgasse, a road whose name resembles Cornelia Street in New York, after which Swift named a song.
"It's a really strange situation and I think the ultimate thing we feel is just grateful that we're safe and that everyone else is safe," she told BBC News. "A bit of a mixed bag of emotions."
She said the cancellation made her feel "probably the most disappointed about anything I've ever been in my life", but she agreed the decision had been made "for the right reasons".
She was one of almost 200,000 fans who were due to attend the three concerts.
Others included Jessica Holroyd, who had flown to the city from Bristol.
"I found out the news when I was in the airport, and I had a bit of a cry in the airport toilets," she said.
"It's all quite emotional. I've been a fan since I was 15 and I'm 32 soon, so it's just quite devastating, really."
Holroyd said the gigs were "such a momentous occasion for loads of people".
"It feels like it might be the only opportunity to see her, particularly the Eras tour, so it just feels like a huge loss."
However, she said she thought Austrian police had "handled it really well".
"And as sad as it is, it seems like the best decision for everyone's safety - the fans and the crew and Taylor, of course. It's not worth the loss of life."
Fans also traded friendship bracelets, some restaurants and coffee shops gave away free food and drink, several museums offered free admission, and a church opened its doors and played Swift songs all day.
"The way Vienna is responding to this and embracing Swifties is so, so, so incredibly beautiful," wrote one fan on X.
"I know it doesn't erase the sadness and fear from having the concerts cancelled for the reason they were cancelled, but by God is it a rainbow amidst this nasty storm."
Natascha Strobl, an Austrian political scientist and author, was planning to go to two of the three gigs, and said she was "absolutely devastated" they were cancelled.
"I was looking forward to it for over a year, and made bracelets and planned outfits and planned the whole day," she told BBC News.
"There are people sitting in hotel rooms who don't know what to do, people who are supposed to fly over who don't know what to do now. They're in shock. There's a lot of crying, of course."
But she agreed that there could be "no debate when it comes to security".
"If it's not safe, it's not safe," she said, explaining that no-one could risk the prospect of a repeat of previous "devastating and shocking" atrocities like at Manchester Arena, when 22 people were killed in a suicide bombing at an Ariana Grande concert in 2017.
Last week, three young girls were killed in a knife attack on a Taylor Swift-themed dance class in Southport.
"Of course, safety is paramount," Strobl said. "But still, we're allowed to feel absolutely terrible about it."
'A tragedy was prevented'
Two suspects, aged 19 and 17, have been arrested.
The head of Austria's domestic intelligence service, Omar Haijawi-Pirchner, told a news conference the 19-year-old had planned to carry out an attack using explosives and knives.
"We have seized these weapons and he considered either possibility and his goal was to kill himself and a large number of people either today or tomorrow at the concert," Mr Haijawi-Pirchner said.
Austrian Interior Minister Gerhard Karner said: "The situation was serious, but a tragedy had been prevented."
Swift's 'biggest fear'
Swift said in a 2019 interview that an attack on one of her gigs was "her biggest fear".
"After the Manchester Arena bombing and the Vegas concert shooting [also in 2017], I was completely terrified to go on tour this time because I didn't know how we were going to keep three million fans safe over seven months," she told Elle at the time.
"There was a tremendous amount of planning, expense, and effort put into keeping my fans safe."
She has not yet commented on the Austrian plot and cancellations.
UK security
The next concerts in the singer's schedule are in London, with five nights at Wembley Stadium from next Thursday.
A spokesman for the city's Metropolitan Police said it worked "closely with venue security teams and other partners to ensure there are appropriate security and policing plans in place".
They added: "There is nothing to indicate that the matters being investigated by the Austrian authorities will have an impact on upcoming events here in London.
"As always, we will continue to keep any new information under careful review."
Chris Phillips, former head of the National Counter Terrorism Security Office, said the incident was "another reminder if we need it that terrorism and Islamic terrorism in particular is still an issue".
However, fans going to the UK gigs should be "no more [worried] today than you were yesterday", he told BBC 5 Live.
"There's an enormous amount of work behind the scenes which you'll never hear about, and you don't even see the results because a success is when nothing happens," he said.
"I imagine as well that Taylor Swift, after the recent events in Southport, would be particularly sensitive to anything like this happening, and so would her management team.
"So maybe that's the rationale behind cancelling these, particularly if they've arrested the two suspects."
- BBC