As you prep for the holiday weekend, look back at the history of Memorial Day through old and new images.

These power duos prove that whether they're tackling global crises or ruling the world, sometimes it takes two. Here's a look at some of the world's most powerful couples.

A treasure trove of rarities, oddities and tech "firsts" has been brought together -- including an experimental 17th century mechanical calculator, a 108-year-old telephone and an incredibly rare, he…