Taking selfies, licking gelato and wheeling suitcases, the hordes of visitors seemed happily oblivious to the possible downgrade UNESCO said was due to the risk of "irreversible" damage.
New York tourist Ashley Park, 28, said she knew it would be crowded in Venice, but it wasn't ruining her vacation.
"Obviously if we lived here with all these tourists it wouldn't be fun," she acknowledged.
Among the crowds on the historic bridge was city worker Diego Nechifrovo, 23, wearing an #EnjoyRespectVenezia T-shirt, who was busy keeping an eye out for misbehaving tourists.
"Sometimes I see someone throwing away his cigarette or walking around without a T-shirt," he said, noticing a bag of potato chips discarded on the doorstep of a jewellery shop.
The worst? One time a family "sat down right in front of the Doge's Palace and started to set up a picnic."
A few weeks ago, a distracted tourist fell into the water, Nechifrovo said.
"He was trying to get a good photo".
Please don't come
Not far away, a seller of watercolours had a sign on his stand pointing to St. Mark's Square.
"That's all they want to know," said the native Venetian, Claudio, who declined to give his last name. "They come to Venice because it's Venice. That's all."
The days of educated tourists visiting and enjoying the city's many churches and museums were over, he said.
"Those who come now don't even know what a museum is. It's not cultural tourism," he said.
"They need to go to the beach, or the mountains, but not here!" he lamented. "Please don't come anymore!"
The list of Venice's challenges are many, from environmental damage to its lagoon to its fleeing residents -- with only about 50,000 left -- leaving what many critics charge is now a city without a soul.
Two years ago, Venice narrowly avoided being placed on the same UNESCO list -- which is intended to spur governments into action to preserve places deemed of "universal value to humanity" -- after the city imposed a ban on massive cruise ships travelling past the centre.
Environmental groups warned the ships, carrying thousands of day-trippers and sailing exceptionally close to shore, caused large waves eroding Venice's foundations and harming the lagoon's fragile ecosystem.
But the rerouting of the ships to the more distant industrial port of Marghera did not address the issue of overtourism itself.
Some 3.2 million tourists stayed overnight in Venice's historic centre last year, according to official data, a number that does not include the thousands of daily visitors who do not spend the night.
"It's pretty beautiful -- it's a draw!" justified US tourist Mike McWilliams, 53, who had just arrived in the city for a two-day visit with his family.
Managing the masterpiece
UNESCO, the UN's cultural wing, put Venice on its heritage list in 1987 as an "extraordinary architectural masterpiece", but it has warned of the need for "more sustainable tourism management".
On Monday, it said progress had been insufficient while citing "a lack of overall joint strategic vision" by authorities.
Critics say measures put in place to check tourism are ineffective and have come too late.
A long-discussed plan to introduce a paid booking scheme for day-trippers has been repeatedly postponed, now until 2024, over concerns it will seriously dent tourist revenue and compromise freedom of movement.
Back at St. Mark's Square, city worker Lorenzo Seano, 21, was struggling to keep tourists from sitting on the steps of the surrounding arcades.
The problem of too many tourists invading cities went well beyond Venice, Seano said, but no one in government had tried to tackle the problem "on a structural level".
"After all, there's a ton of money coming in," he said.
