Photos of the week: 5/20 - 5/27

As we head into Memorial Day, take a few minutes to look back at the past week's biggest news stories through photos -- including President Obama's historic visit to Hiroshima, the ongoing campaigns by the remaining three presidential candidates, severe weather from Knasas to Costa Rica and the ever-popular National Spelling Bee that took place on Thursday.

Click through the slideshow above to see the best photos from all of these stories and more, and be sure to check back next weekend for our selection of the best photography from the coming days.