People around the world have been celebrating St Patrick's Day, with more than half a million people packing out Dublin city centre for the party, while in Britain the Duchess of Cambridge handed out shamrocks to soldiers.
The Irish capital's parade was the symbolic centrepoint of celebrations that stretched across the globe, with Ireland putting aside its economic woes for a day of good "craic".
Landmark sites throughout the world, including the Leaning Tower of Pisa, Niagara Falls, the London Eye, the Burj al Arab hotel in Dubai, the Cibeles fountain in Madrid, the Palace of Culture and Science in Warsaw and Table Mountain in Cape Town have been illuminated green to mark the day.
"What other country can bring people from all around the world to celebrate its own culture?" said Stephanie Reimer, from Canada, who was watching the parade in Dublin.
She and a group of friends, dressed from head to toe in green, had the best view of the two-hour parade where it snaked across the River Liffey on the O'Connell Bridge.
"What I love about St Patrick's Day is that it's an inclusive celebration that invites absolutely everyone and allows us all to be Irish for a little while," she added.
In Britain, the Duchess of Cambridge, presented traditional sprigs of shamrock to members of the 1st Battalion Irish Guards, and met their regimental mascot, an Irish wolfhound called Conmeal.
Her husband Prince William is the regiment's honorary colonel.
The Duchess looked at ease at the Battalion's home base in Aldershot, Hampshire, as she continued the Royal tradition which dates back more than 100 years.
She wore a green Emilia Wickstead dress coat bought especially for the occasion, with a brown Lock & Co hat, brown suede shoes and a gold shamrock brooch, which has been handed down through the royal family and was once worn by the Queen Mother.
Back in Dublin, resident Rory Larkin said it was the colours, sounds and electric atmosphere that attracted him and his family to the city's parade each year.
"It makes you proud to be Irish," said Mr Larkin, with a tricolour-painted face and his hair dyed green.
"No matter what kind of rubbish we've got going on in politics and the economy, no matter how gloomy it all seems, this is something to be proud of and to know that the world is watching us today," he added.
The city's two most popular tourist attractions, the Guinness brewery and Dublin Zoo, both offered nods to the day's mix of patriotism and partying.
Zoo animals were being fed special mixes of oranges and vegetables, mimicking the green and orange of the Irish flag, while Guinness was offering free admission to any visitors named Patrick.
At least 60 million people worldwide claim Irish heritage - some 34 million people in the United States alone. That is about eight times the population of the Republic of Ireland.
The US is also celebrating, with eyecatching parades in Chicago and New York.
Taoiseach Enda Kenny is in the US where he is due to present the customary bowl of shamrock - Ireland's three-leafed emblem - to President Barack Obama at a celebration in the White House on Tuesday.
Mr Obama has links with Ireland through an ancestor who emigrated from the small midlands town of Moneygall in 1849 and he visited the country last year to meet some of his cousins.
In his message for the national holiday, President Michael D Higgins said Irish people had a "love for life", a "sense of fun" and an "innate spirit of hope and optimism".
"The Irish are an enterprising and resilient people. While navigating very difficult economic conditions, we refuse to succumb to defeat or fatalism," he said.
"This indefatigable spirit has in the past ensured our survival and is now a source of our creativity and purpose."