St. Patrick’s Day, the annual celebration of all things Irish, is being marked in cities across the country on Monday with boisterous parades and celebrations.

Paul Healey, of Holbrook, walks with friends toward the action of the St. Patrick’s Day Parade, in South Boston. – Pat Greenhouse/ The Boston Globe Participants dressed as Min

It was among Irish American communities that the day became the celebration it is, from its roots as a more solemn day with a religious observance in Ireland.