Here are some facts you may not know about St. Patrick's Day.

St. Patrick wasn't actually born in Ireland. He was born in England but was kidnapped as a teen and taken to Ireland as a slave.

He later escaped and became a priest and eventually the patron saint of Ireland.

The first St. Patrick's Day in the U.S. was held in Boston in 1737.

The first official parade was held in New York City in 1762.

Today, the parade goes up Fifth Avenue from 44th Street to 79th Street, and about 150,000 people march.

Two million people will watch and celebrate the parade in the city.

The St. Patrick's Day parade is the world's oldest and largest parade.