​Calendar: Week of April 20

Here's a look at the week ahead on our "Sunday Morning" Calendar:

Monday is the day for the Boston Marathon, the second race since the 2013 bombing ... and the first since the conviction of Dzhokar Tsarnaev for his role in the attack.

Tuesday is Queen Elizabeth's 89th birthday, though the official celebration won't be held until June. Already the oldest monarch in British history, she'll also become Britain's longest-reigning monarch this September.

Wednesday is International Earth Day. Backers say more than a billion people in 192 countries will be taking part in activities to protect the environment.

Thursday sees the 10th anniversary of the very first YouTube clip ... a posting by co-founder Jawed Karim entitled "Me at the Zoo."

Friday is Tax Freedom Day, the date on which Americans are calculated to have collectively earned enough money to pay all their taxes and start earning money for themselves.

And on Saturday, an exhibition of 32 Andy Warhol Campbell Soup can paintings, among other works, goes on display at New York's Museum of Modern Art.