By Cherri Gregg

PHILADELPHIA (CBS) — Today will mark Philadelphia’s 245th annual Saint Patrick’s Day Parade.

It began in 1771 and is the second oldest in the nation and one of the largest. 20,000 people are expected to march with more than 150 groups taking part.

The parade route begins at 16th Street and JFK Boulevard and will go down the Ben Franklin Parkway and around Eakins Oval to the Philadelphia Museum of Art.

The theme for this year’s parade is “Saint Patrick Bless, Strengthen and Pray For Our Families.”

There are lots of festivities to celebrate today, including a Saint Patrick’s Day Mass at 9:15 a.m. at St. Patrick’s Church at 20th and Locust Streets, as well as a leprechaun run at 9 a.m. on West River Drive.