Keen on Keys?

Today I'll point you to Slate.com for a History of Keys. Click on the picture of a key that looks interesting to learn more. It will open a slideshow with a description on the upper right. For example:

In the medieval period, keys were more commonly made of iron than bronze, but they retained both their practical and symbolic purposes: securing valuables and showing that you were important enough to have valuables to secure. One way to convey your significance in this period? By carrying a really big key.