Nation decks out in green for St Patrick's Day festivities
Performers are ready to wow crowds as we celebrate St Patrick's Day
Rusty Viking ships and a majestic metal stag were among the floats in today's parade.
The 2014 parade theme is 'Let's Make History' and for Waterford-based street theatre company Spraoi that meant looking to legendary warrior Brian Boru and legendary rugby player Brian O'Driscoll.
"The Battle of Clontarf is the inspiration," artistic director Mike Leahy explained.
"But we thought we'd give it a bit of a rugby twist with the week that's in it so we have the Leinster colours on the masts of the ships."
Over 90 actors and dancers performed this afternoon alongside the colourful tall ships while a harpist sat at the prow and serenaded the 500,000-strong crowd.
Spraoi joined seven other theatre companies on the parade route including renowned theatre company Macnas and the Inishowen Carnival Group's float 'The Merman's Tale', which was scattered with lobster pots, fragments of shipwrecked boats and colourful fish tails.
Eleven marching bands strode along the 2.6km parade route while champion cyclist Stephen Roche acted as 2014 Grand Marshal.
"I've been doing this for 18 years," Mr Leahy said. "There's always some waiting around at the start but once you're on the route and screaming at the throngs of people, it goes by in the blink of an eye."
The Dublin parade was one of the largest in the world, where the theme was Let's Make History and the first of a three-year programme.
The next two years will look at the present and future.
Dozens of elaborately decorated floats portrayed the theme and colour of a carnival while marching bands entertained one of the biggest crowds in the city for the March 17 festivities.
President Michael D Higgins attended the event with his wife Sabina and urged people to think of those who have emigrated from Ireland in recent years.
"It continues to play a significant role in defining us as a society and as a people," he said.
"Today we celebrate our wider and diverse Irish family, to whom we remain connected by a strong cultural heritage and history. We are grateful for all they do to keep that heritage alive in their adopted homelands across the globe, as well as for their interest in, and tangible support for, Ireland's welfare and development.
"Today is a special day for all those Irish communities great and small across the world that come together in a spirit of pride and joy to celebrate their identity and their links of affinity and affection with their homeland of origin."
The parade from Dublin was streamed online to a worldwide audience and an Irish diaspora of about 70 million.
St Patrick's Day celebrations kicked off last night as the Great Wall of China became the latest UNESCO world heritage site to 'go green' as part of Tourism Ireland's 'Global Greening' project.
Now in its fifth year, the project has seen some of the world's most iconic landmarks – including Niagara Falls, New York's Empire State Building, the Treasury in the ancient city of Petra, the Tower of Hercules in Galicia and the Moulin Rouge – bathed in green light over the course of the St Patrick's weekend.
More than 100 international landmarks were turned green to mark St Patrick's Day, including the Great Wall of China, and not to ignore the celebrations the Irish cricket team weighed in with a nail-biting victory over Zimbabwe in the World Twenty20 competition.
While an influx of tourists has poured into the country, 417 Irish soldiers on 16 different peace support missions will celebrate in different corners of the globe.
In Mogadishu, Somalia, the Irish contingent who are serving as part of the EU Training Mission are hosting an Irish Sports Day for their international colleagues.
The competitors will take part in a fun run, followed by a strongman competition and finishing with a 'How Irish are you?' quiz.
The 179 Irish troops in 'Camp Shamrock' based in south Lebanon celebrated St Patrick's Day with a blessing of shamrock by Unit Chaplain Fr PJ Sommers.
In Pristina, Kosovo, St Patrick's Day was celebrated on March 15 with a Shamrock Parade.
The earliest parade was held in Dingle, Co Kerry at 6am while the shortest took place in West Boylston in the US state of Massachusetts, where 200 people marched through a car park between two pubs in the town Finders and Keepers.
Meanwhile, in a St Patrick's Day message Taoiseach Enda Kenny said Ireland was known around the world for its people and their ability to change other people's circumstances.
Mr Kenny said: "That our small Atlantic island should inspire so much global affection is due in no small part to the nobility, or the uaisleacht, of our people who time and again saw to it not just to make the difference but to be the difference in parts of the world visited by war and famine and destruction."
"Even now as I speak in remote field-clinics and feeding stations and in border crossings there is an Irishman or Irishwoman bringing not just help but confidence, not just hope but indeed love."
Mr Kenny, who is in the US for the weekend, also used his address to say thank you for the sacrifices made in Ireland since the economic crisis.
"I know the process of transforming Ireland has been extremely difficult, many aspects galling for you. The shock of the fall was followed by the seemingly endless sacrifice by you and your families," he said.
"We are at last and thanks to you and to your patience and your resolve putting Ireland first. We are now back on the road to recovery."
The Taoiseach's attendance in New York has been clouded by a row about a ban on lesbian gay bisexual and transgender (LGBT) organisations marching in the Manhattan parade with equality banners.
New York City mayor Bill de Blasio has refused to take part in what is the world's oldest and biggest St Patrick's Day event and Guinness withdrew sponsorship of the parade.
One of the biggest parades in Northern Ireland was held in Downpatrick, Co Down, where an estimated 30,000 people crowded the streets.
Dr Tim Campbell, director of the town's St.Patrick's Centre, said: "We've taken the politics out of the day, and many other towns are following in our footsteps. We just want people to have a fun day."
There were parades as well in Omagh, Strabane, Enniskillen, Armagh and Londonderry.
Belfast's held its St Patrick's Day parade - one of the biggest ever, according to Lord Mayor Mairtin O'Muilleoir - yesterday.
A small crowd of loyalists, some carrying Union flags gathered outside City Hall today. There was a heavy police presence in the area to prevent any trouble.
Organisers of the Dublin parade put the crowds at more than half a million - well up on last year's figures.
More than 3,000 performers took part in the carnival, with Irish sporting hero, Tour de France winning cyclist Stephen Roche the grand marshal as Ireland welcomes the Giro d'Italia bike race in a few weeks.
Susan Kirby, St Patrick's Festival chief executive, said: "The festival parade is true testament to the artistic talent we have here in Ireland, talent that is showcased on a global stage today as the parade is viewed by millions the world over."
A number of marching bands earned awards for their performances at the parade including the Owasso High School Marching Band, from Oklahoma in the US which was picked the overall best band while the Spirit of the Parade Award went to the Clondalkin Youth Marching Band, from Dublin.