And there came a day, a day unlike any other, when Earth's mightiest heroes and heroines found themselves united against a common threat. On that day, the Avengers were born-to fight the foes no single super hero could withstand!" As the Heroic Age dawns on the Marvel Universe and we prepare for a new chapter in the ongoing saga of Earth's Mightiest Heroes, each Friday Marvel.com will present a different column focusing on the one and only Avengers. From line-ups to costumes to villains to classic stories and beyond, we've got you covered on the history of Marvel's most prolific team of heroes!