Britain spent nearly nine billion pounds ($14.42 billion) to create a magical and ambitious wonderland of venues for the 2012 Olympic Games, where fans were thrilled across a capital whose grime and grandeur alike got a makeover of global glamour.
The Games proved a timely shot in the arm, spiritually if not financially, for a bruised nation struggling with economic recession. The government, citing figures that were all but unmeasurable, said they would even deliver monetary benefits, to the tune of some $20 billion, though others were sceptical.
As for sport, the cash delivered a gold rush of medals for the somewhat startled hosts - placing them third, their best result since 1920, if well behind the table-topping United States and China, which returned to the number two spot after dominating its home Games in Beijing four years earlier.
More importantly, though, the July and August Games gave Britain - and Britishness - a reputational boost, at home and abroad, at a time when few who are younger than the 86-year-old Queen Elizabeth can recall its days of imperial glory.
Instead, 2012 showcased a new, modern London as a tolerant, welcoming and multicultural city.
Britain delivered, or, as the otherwise rather beleaguered Prime Minister David Cameron put it after the Games: "We showed the world what we're made of; we reminded ourselves of what we could do."
Many overseas agreed. Recalling prophecies of doom, about terror and traffic and Londoners' deep reserves of cynicism and, well, reserve, Italy's Corriere della Sera declared: "Thank you, London - A lesson to the pessimists ... When it comes to parties, festivals and ceremonies, no-one can match the British."
"The neo-British...are emotional," marvelled the Italians, traditional champions in the heart-on-sleeve stakes. "They feel the tension beforehand; they weep on the podium and watching the television; they put down their beer and hug their neighbour."
What the investment left behind was an unforgettable sporting tapestry of tears, drama and raw emotion played out against backdrops from Buckingham Palace to a grand new stadium where factory hulks once blighted the blitz-scarred East End.
These were the Games that Olympic chief Jacques Rogge called "happy and glorious", echoing Britain's national anthem "God Save the Queen" as Elizabeth celebrated 60 years on the throne.
They opened with seven young, unknown athletes lighting the cauldron and had as their motto "Inspire a Generation".
As he closed the Games, Rogge said: "The human legacy will reach every region of the world.