Metal Body Suits vs. Weapons of Medieval Destruction discusses the evolution of armor through the Middle Ages. While it is a very brief overview — focusing more on late medieval plate armor — the article does provide a host of images to supplement the text.
The focus of my studies tends be on medieval England and France during the High Middle Ages, before this type of plate armor even existed, but some of the pieces of armor shown here are so outrageous, I just had to share the link. I didn’t realize such decorative helms even existed. Were they actually worn into battle, or were they just show pieces? Maybe someone more knowledgeable on the late medieval period (particularly armor) can comment.
*the photo is of the armet of Henry VIII (Innsbruck, Austria); image retrieved from the site linked above