The Garden Bridge project proposed by actress Joanna Lumley has been abandoned amid bitter recriminations over the "waste" of taxpayers' cash.
Backers of the controversial plan conceded defeat and closed down the charity set up to build and run the crossing in the centre of London .
The plans, which were supported by former London mayor Boris Johnson , were effectively killed off by his Labour successor, Sadiq Khan , in April when he refused to provide guarantees for the costly crossing.
Mr Johnson said it was "so sad" that Mr Khan had "killed it out of spite" while the Labour mayor said Londoners would be "very angry" that taxpayers had lost tens of millions on a project that has come to nothing.
A City Hall source claimed the bridge was a "Boris vanity project" and said Mr Khan had been "crystal clear since before he took office that he was not prepared to commit new taxpayers' money to the project".
The Garden Bridge Trust (GBT) said it was a "sad day" for London because the failure to build the bridge sent a "message to the world that we can no longer deliver such exciting projects".
Mr Khan said in April he would not provide support for the plans because it would leave taxpayers in the capital at risk of higher bills. More than £37 million of public money had already been spent on the project.
It followed a damning report by Dame Margaret Hodge that recommended ditching the proposed Thames crossing because it was "difficult to justify further public investment" in the bridge, which was likely to end up costing more than £200 million.
Mr Johnson, who backed plans for the bridge in 2013, said: "So sad Sadiq Khan has killed garden bridge and wasted so much time and money. Labour has no vision for London and no ambition.
"The garden bridge was a beautiful project and could have been easily financed.
"The Labour mayor claimed to support it but killed it out of spite because it was not initiated in his period of office.
"I would also like to thank especially the donors and trustees who persevered for so long.
"They took seriously the Labour mayor's protestations that he supported the project.
"Indeed TfL has spent £10m in the last year on the strength of those assurances.
"The only crumb of comfort is that good plans have now been developed and can be readily revived."
Mr Khan said: "It's my duty to ensure taxpayers' money is spent responsibly.
"Following the very serious issues highlighted in Dame Margaret Hodge's independent review of the bridge, including a funding gap of over £70 million, potentially unlimited costs to London taxpayers to fund the bridge in the future, systemic failings in the procurement process and decisions not being driven by value for money, I could not permit a single penny more of London taxpayers' money being spent on it.
"I have been clear since before I became mayor that no more London taxpayers' money should be spent on this project and when I took office I gave the Garden Bridge Trust time to try and address the multiple serious issues with it.
"Londoners will, like me, be very angry that London taxpayers have now lost tens of millions of pounds committed by the previous mayor on a project that has amounted to nothing."
Chairman of the Garden Bridge Trust Lord Mervyn Davies said: "We are incredibly sad that we have not been able to make the dream of the Garden Bridge a reality and that the mayor does not feel able to continue with the support he initially gave us.
"We had made great progress, obtaining planning permission, satisfying most of our planning conditions and we had raised £70 million of private money towards the project."
In a joint statement, Vauxhall MP, Kate Hoey, and Lambeth Councillors, Jennie Mosley and Kevin Craig criticised The Garden Bridge Plans and called for a full public inquiry and "accountability for the Garden Bridge Trustees in respect of lost taxpayers’ money."
They said: "The Garden Bridge was not needed and was clearly a vanity project. There was never a need for a bridge in this location.
"The Garden Bridge Trust project was poorly managed, expensive and an inappropriate use of taxpayers’ money.
"The Garden Bridge project was rushed through by the previous Mayor, Boris Johnson, neglecting appropriate scrutiny and due process. We welcome and support the findings of the Margaret Hodge Report and Sadiq Khan’s recognition of the lack of viability of the project.
"The Garden Bridge would destroy a much loved area on the South Bank with precious mature trees.
"Opposition to the Garden Bridge was ignored and misrepresented by the Garden Bridge Trust.
"The Garden Bridge Trustees have been irresponsible in their use of taxpayers’ money by spending public money on securing large scale contracts before they had secured the land on the South Bank.
"In conclusion, we never had any doubts that the Garden Bridge Project would fail but we are disappointed that the project has been allowed to get this far, by the Trustees, to the extent that £50million of taxpayers money has been lost which could have been so much better spent."
Keep up to date with the latest news from around the county via the free Get West London app.
You can set up your app to see all the latest news and events from your area, plus receive push notifications for breaking news.