Check out how celebrities enjoyed the Irish festival with friends and family.
Claims that Irish people were sent to the colonies as slaves have been rejected by historians.
England star accidentally uploads flag of Ivory Coast while celebrating Ireland's national day.
From London to Ireland and as far away as Boston, there's somewhere to celebrate wherever you are.
A number of other Irish-themed searches spike over the celebration.
The Duchess chose not to present the clover to the Infantry Battalion.
The annual St Patrick's Day parade in New York City will take place on 17 March along 5th Avenue.
Barack Obama hints at Trump while condemning 'vulgar and divisive rhetoric' in presidential campaign
The president also criticised anti-Trump supporters for resorting to violence in their protests.
Time, date and parade route of the New York City St Patrick's Day parade on 17 March 2016.
The advertisements which were placed around Toronto metro in Canada have been removed.
Organisers saying more than 100,000 people were due to take part.
The St Patrick's Day Festival and Parade will take place on Sunday 13 March.
The duchess also pinned a traditional sprig on the battalion's wolfhound mascot Domhnall.
Kate Middleton decorates the regimental mascot, an Irish Wolfhound named Domnhall, with shamrocks.
These celebrities have all had their ancestry traced back to Ireland.
For the first time in the 114-year history of Boston's St. Patrick's Day parade, gay rights activists marched openly.
St Patrick's Day is celebrated by Irish nationals around the world on 17 March.
Parade organisers confirm openly gay group to march through New York for first time
Cath Everett watches a 'Fake Irish Accent' competition and dodges men dressed as leprechauns
Duchess of Cambridge decorates Mons Barracks in Aldershot mascot, an Irish Wolfhound, with national emblem of Ireland
Best photos of the day: 17 March 2014.
NYC and Boston embroiled in gay rights furore after both cities deny equality groups right to march
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Landmark buildings including the London eye were all illuminated with green lights.