It’s a growing tourism trend that should probably carry a health warning – sticking used chewing gum to walls close to popular attractions. The Italian city of Verona has become the latest destination targeted by tourists who want to leave their mark – and possibly their DNA – on the city’s ancient walls.Thousands of pieces of chewed gum – in a variety of different colours – have now been pressed against the 13th century walls of Via Cappello, at the exit point of one of Verona’s most ‘viral’ attractions. Casa di Giulietta – ‘Juliet’s Balcony’ – has gained cult status with Shakespeare fans because it bears a striking resemblance to the one described by the Bard in Romeo and Juliet. A tourist in Verona this week pictured sticking gum to the 13th century walls outside Juliet’s Balcony on Via Cappello in the historic Italian city Several of the ancient city walls in one of the busiest tourist thoroughfares in Verona are now covered in pieces of chewed gum – as visitors pay tribute to the tale of Romeo and Juliet by leaving their gum (and DNA) behindWhile there are no official links between the play and the marble balcony, it hasn’t dissuaded tourists from making a romantic pilgrimage to glimpse the 13th century building it protrudes from – and sticking gum nearby in honour of the star-crossed lovers. Chewing gum walls have become increasingly popular in major tourism cities across the world, with the bacteria-laden phenomenon thought to have started in the early nineties in Seattle.When it comes to being one of the most unhygienic attractions in the world, the gum mural, which is sited in an alley close to foodie hotspot Pike Place Market in the US west coast city now eclipses even Ireland’s Blarney Stone – where tourists are invited to kiss a 330-million-year-old carboniferous limestone for good luck – for germ potential. Since the Casa di Giulietta – ‘Juliet’s Balcony’ – became a paid-for attraction, the walls of the street nearby have become covered in pieces of chewing gum US export: Seattle’s Gum Wall started in the early 90s and, despite the best efforts of the city to remove it, remains a place tourists keep adding to A tourist at Seattle’s Gum Wall blows a big bubble before sticking it to the wall close to Pike Place Market in the cityThe Seattle walls first became a vertical dustbin for attendees looking to ditch their chewing gum before entering the theatre that sits behind them – and it quickly grew into a colourful blur of gum and notes, which many have deemed ‘art’ in the years since. By the outbreak of the Covid pandemic, Seattle’s Gum Wall had grown so much that officials in the city ordered a vast clean-up.In 2020, it measured eight feet in height and over 54ft wide, with an estimated one million pieces of chewed gum stuck to it. An industrial steam machine was deployed to melt the gum at 280 degrees in order to remove it but, six years on, the Seattle Gum Wall is bigger than ever. And over in San Luis Obispo in California, a similar wall of gum has sprung up and is now known as ‘Gum Alley’Judging by photos taken this week showing tourists leaving freshly chewed gum in Verona, copycat Gum Walls have now firmly arrived on European soil.Prior to Juliet’s Balcony becoming a paid-for attraction in 2025 – visitors now pay 15 euros (£12.80) to get close to the balcony, which was actually constructed in the 20th century using 13th century marble, graffiti covered the courtyard walls close by.Those walls have since been cleaned up and are no longer accessible to passersby, who’ve instead turned their attentions to the main street, Via Cappello, and swapped Sharpie pens for their favourite gum brands. What do healthcare professionals make of tourists’ passion for sticking old gum laced with their saliva to public walls?NHS GP Dr Ellen Welch tells the Daily Mail: ‘It should go without saying that a wall covered in chewing gum from hundreds of people is a potential hotbed for bacteria, and extremely unhygienic. ‘Research has shown that chewing gum can continue to contain and attract harmful bacteria for a long time after it is disposed of.’The doctor, who is the resident medical expert for holiday insurance company Total Travel Protection, advises caution when visiting, saying: ‘It’s a good idea to avoid contact with chewing gum walls, and you should certainly not touch them. ‘Doing so carries a high risk of being exposed to a huge amount of bacteria and any number of potential illnesses.’You should avoid adding to a chewing gum wall as it can both expose you to bacteria on the wall, and risk spreading any bacteria you are carrying to others. ‘The original Seattle wall for example, is cleaned fairly frequently due to the fact it is known to attract pests.’For romantically-inclined travellers, the trend for leaving gum appears to be replacing the padlock trend which reached its peak in around 2015 before cities cracked down on tourists who attached locks to key tourist sites. Pont des Arts bridge in Paris became the location for another viral trend – attaching a padlock to the bridge as a sign of romance, until Paris officials said the structure might be damaged permanently by the weight of the momentoes, and they were removed in 2015Most famously, the Pont des Arts bridge in Paris became a pilgrim site for lovers with thousands leaving their often heart-shaped mementoes on the bridge. However, the collective weight of the locks became so heavy that the city’s council said the 19th century bridge was at risk of being damaged – and they were removed by a team of workers armed with bolt cutters just over a decade ago. The council’s initiative was in response to a ‘No Love Locks’ campaign on Facebook by Parisians who said they were tired of the practice, which they claimed had turned tourist attractions into ‘eyesores’. The bridge was then fitted with ‘padlock-proof’ plexiglass in an effort to thwart tourists doing it all over again.