Legend has it that St. Patrick was kidnapped by pirates and taken to Ireland. He escaped, but returned years later to convert the Irish to Christianity. In Dublin, as in cities around the world, what was once a solemn celebration of a saint is today most commonly paired with drinking green beer, shamrocks and leprechauns. 

Dublin IRELAND-ST PATRICKS Day parade March 17 2016

(Clodagh Kilcoyne/Reuters)

St. Patrick's Day has shifted from sacred to secular.

Parades, parties and horse races? The annual Cheltenham Festival horse races in the U.K. are a St. Patrick's Day staple that attracts top Irish teams, and race goers like Paddy Cusack, alike.

St patricks day Cheltenham festival UK March 17 2016

(Dylan Martinez/Livepic/Reuters)

St. Patrick is believed to be buried in Downpatrick.

St. Patrick, who was a medieval bishop elevated to the patron saint of Ireland, is still celebrated on March 17 — the date on which he is believed to have died. The celebration features a wreath laying and pilgrimage to his grave, which is located at Down Cathedral, in Northern Ireland.

St Patricks Day service of remembrance northern Ireland March 17 2016

(Charles McQuillan/Getty)

One St. Patrick's Day parade now looks much like the others.

The Irish diaspora to North America is credited with transforming the day, which wasn't recognized with a parade in Ireland until the turn of the 19th Century. In Dublin, where parade-goers heard this brass marching band, the celebrations looked much as they do in North American cities.

IRELAND-ST PATRICKS Day parade in Dublin March 17 2016

(Clodagh Kilcoyne/Reuters)

St. Pat's parades began in New York… or maybe it was Boston?

The first St. Patrick's Day parade was likely held in New York City in 1762, according to the parade's official website. 

According to organizers of Boston's annual march, it wasn't until 1901 that the first official parade was held in that city, although there are references to homesick Irish immigrants recognizing their patron saint as early as 1737.

In New York, which also lays claim to the nation's largest St. Pat's parade, the annual celebration marched down Fifth Avenue at its customary start time of 11 a.m. ET on Thursday.

St Patricks Day Parade New York March 17 2016

(Mary Altaffer/AP)

St. Patrick's Day is now less about the man and more about all things Irish.

St. Patrick is also the patron saint of New York and the state's archbishop, Cardinal Timothy Dolan, serves as the city's parade Grand Marshall. That's him on Fifth Avenue.

ST PATRICKS Day New York Cardinal Timothy Dolan Archbishop of NY March 17 2016

(Mike Segar/Reuters)

Prince William handed out shamrocks.

As is customary, Prince William took part in a St. Patrick's Day parade at the Irish Guards at Cavalry Barracks, in west London, wearing a sprig of shamrock on his hat.

BRITAIN-ROYALS St Patricks Day March 17 2016 Prince William

(Heathcliff O'Malley/Reuters)

Celebrations were held around the world.

Traditional Irish dancers, like this troupe performing outside an Irish pub in Sydney, Australia, are these days as commonplace as Guinness and shamrocks at St. Patrick's Day celebrations the world over. 

St Patricks Day Sydney Aus March 17 2016

(Brendon Thorne/Getty)

Irish heritage was on display in Toronto, too.

A convoy of DeLoreans, which were built in Belfast in the early 1980s, are a St. Patrick's Day parade tradition in Toronto and rolled down Yonge Street on Sunday.

DeLorean DMC-12 St Patricks Day parade Toronto

(Bruce Reeve/CBC)

Meanwhile, in Kitchener-Waterloo…

Police weren't taking any chances as students in the university town prepared for St. Patrick's Day parties. Last year, campus police at Wilfrid Laurier University, as well as City of Waterloo bylaw officers, laid nearly 270 alcohol-related charges including 204 having to do with possession of open alcohol.