Taylor Swift's "Eras" tour wraps up its European leg in London on Tuesday, after the American megastar wowed hundreds of thousands of fans across a dozen countries.

"I wish I could have toured Europe more. This is a dream crowd," the 34-year-old singer told fans at Paris's La Defense Arena, where she kicked off the run of shows in May.

Four months later, here are five takeaways from Swift's time in Europe, as she goes out in "Style" in front of a 90,000-strong crowd at the British capital's Wembley Stadium.

 'Swiftonomics' 

From "Swiftflation" to economic boosts, European cities saw hotel prices soar as fans descended from around the world.

Heeding Swift's song lyric "grab your passport and my hand", 120,000 Swifties travelled from 130 countries to Stockholm in May, where they were expected to spend half a billion Swedish kronor ($46 million), according to the Stockholm Chamber of Commerce.

Hotel rooms also saw a price spike of "approximately 295 percent", the chamber's chief economist Carl Bergkvist told AFP, with some economists fearing the Swift craze could send Swedish consumer prices rising again.

Two concerts in Madrid are estimated to have injected 25 million euros ($27.6 million) into the Spanish capital's economy.

And the tour was forecasted to boost the UK economy by almost £1 billion ($1.3 billion), Barclays bank said in a study titled "Swiftonomics".

 'Shake it off' 

Seismologists across the continent recorded Swifties literally making the ground shake.

In Lisbon in May, concerts triggered seismic activity detected up to six kilometres (four miles) from the stadium. The strongest activity was recorded appropriately during the song "Shake it off", reaching a magnitude of 0.82 on the Richter scale.

In Edinburgh, the British Geological Survey revealed fan favourites "Ready for It?", "Cruel Summer" and "Champagne Problems" resulted in the "most significant seismic activity".

During "Ready for It?", the crowd in the Scottish capital transmitted approximately 80 kilowatts of power -- equivalent to some 6,000 car batteries, the geologists said.

 Foiled attack

The last month of the Europe tour was marred by a foiled suicide attack plot, with Austrian authorities revealing that an Islamic State-sympathiser was planning a deadly attack at a Swift concert in Vienna.

Three suspects were detained and all three August concert dates in Vienna were cancelled following an investigation conducted with the help of US intelligence.

Disappointed Swifties tried to lift their spirits by gathering at Vienna's Corneliusgasse -- dear to Swift's fans for its resemblance to her hit "Cornelia Street" -- to chant the pop star's songs and exchange bracelets with each other, an Eras Tour tradition among fans.

 Knife tragedy

Tragedy struck when three girls were killed in a stabbing in the northwest English town of Southport at a dance class themed around Swift on July 29.

"The horror of yesterday's attack in Southport is washing over me continuously, and I'm just completely in shock," Swift wrote in an Instagram post, ahead of a concert in Warsaw, Poland.

Swift met two survivors of the attack during her August shows in London, with a mother posting pictures on TikTok of the girls backstage with Swift after a concert, Rolling Stone magazine reported.

Her fans raised nearly £400,000 for the victims under the banner "Swifties for Southport".

 'Tay-gating' 

Ticketless fans dressed up and exchanged bracelets as they listened to concerts from outside stadiums in a practice known as "Tay-gating".

In Madrid, Swift noted around 50,000 "people came out and listened to the show" from a nearby hillside on both nights, "participating in the show from afar".

Officials in London and Amsterdam warned fans not to gather outside venues though, citing disruption to local residents.