Cheers and confetti filled New York’s Times Square when the traditional midnight drop of a multi-coloured crystal ball signalled the start of 2010 and a fresh decade.
The city was on high alert following the alleged Christmas Day attempt by a Nigerian man to blow up an airliner bound for Detroit.
Hundreds of uniformed and undercover police, as well as radiation detectors and sniper teams, monitored the enormous crowd, which braved snow and rain to attend the party.
Dublin was treated to a spectacular display at Guinness’ St James’s Brewery as the 250th anniversary was brought to an end.
A live television broadcast featured a 42-metre long recreation of Arthur’s famous signature in pyrotechnics across the east facing wall of Guinness Storehouse, followed by fireworks from the rooftop of the building.
In London, more than 200,000 people lined the banks of the River Thames to watch fireworks explode from the London Eye, the giant Ferris wheel across from the Houses of Parliament and Big Ben.
As many as 80,000 people turned out in the Scottish capital for the Hogmanay festivities as they watched fireworks at Edinburgh Castle.
Earlier, some 120,000 Russians gathered on Moscow’s Red Square to toast 2010 and hear words of encouragement from President Dmitry Medvedev, whose country is in an economic slump.
“The past year was not a very easy one for our country, and I want to thank you all for bearing up together,” he said the traditional presidential new year address.
In Australia, about 1.5 million people lined Sydney Harbour to watch fireworks from the Sydney Harbour Bridge and four barges.
Thousands of people crammed into Hong Kong’s harbour, where 9,000 fireworks were unleashed from the city’s tallest skyscraper and other buildings.
In Paris, about 70,000 people gathered near the Eiffel Tower for a light show, while more than 8,000 police were deployed across the city and suburbs.
Cars were burned throughout France, with hundreds of people arrested, but trouble was not as bad as in previous years.
Pope Benedict XVI, in traditional prayers in St Peter’s Basilica on the last day of the year, called on Christians to help families hit by economic difficulties and unemployment.
In Berlin, more than one million revellers gathered on the boulevard leading to the Brandenburg Gate with live bands and DJs.
In Spain, which took over the shared EU presidency at midnight, thousands of people attended a light and sound show at the central Puerta del Sol square where a giant image of the EU flag was projected onto a building.
“This is the best street party in the world. Now I am going to work on my first hangover of 2010,” said Gerry Shalloe, a 32-year-old English teacher from Ireland who lives in Madrid and who attended the countdown with friends.
In Poland, some 90,000 people ushered in the new year at a concert in Warsaw in memory of Michael Jackson attended by the late pop singer’s sister La Toya.
Ukraine’s President Viktor Yushchenko, facing an uphill re-election bid on January 17, used his address to argue for the ex-Soviet republic’s push to join the EU and NATO.
US jitters after the Christmas airliner bomb plot rose again on Wednesday when New York police ordered the brief evacuation of Times Square and investigated what they said was a suspicious van – which later proved to be harmless.
In Pakistan, the new year was overshadowed in Karachi by a suicide attack during a holy Shi’ite Muslim ceremony on Monday that killed 43 people.
In Afghanistan, US-led soldiers were on alert after two militant attacks claimed the lives of eight Americans and five Canadians, while two French journalists were reported kidnapped by Taliban.
And in South Africa, President Jacob Zuma used his New Year message to rally for unity for the 2010 football World Cup – the first ever to be held in Africa.
At midnight in Rio de Janeiro, about 2 million people gathered along the 4km Copacabana beach to watch a huge fireworks display.
New Year’s Eve also presented the world with a Blue Moon, the name for a second full moon in one single month, the first time in 353 years the world has seen one for new year’s.