Here is where one of the brave souls to take up the mantle of Scirocco stood against, and fell to, the Rikti invaders.
The Undefeated Badge is in the Promenade neighborhood of Atlas Park. It is located on top of the building closest to the Steel Canyon entrance tunnel, under the right (southern) side of the billboard. There is a fire escape the non-airborne heroes can use to get to the roof.
Its coordinates are (545, 59, -2,306).