While there are so many fantastic images to choose from, I think the most awe-inspiring image that we, as a species, have created is the Hubble Ultra-Deep Field.
This is a long-exposure photo taken of a very small patch of what appeared to be empty space (its size is about equal to a 1mm x 1mm square held at arms length; or 1/13,000,000 of the night sky). The length of the exposure lasted from September 24, 2003; all the way through to January 16th of 2004. What it captured was nothing less than the nascency of the universe; galaxies of some 13 billion years in age (and in LY distance from us).
Nothing else can quite rival the scope of this image. While the Pale Blue Dot looks inward to reflect on our relative insignificance (and is quite impactful in its own right), the HUDF generates the same effect whilst looking outward. There are no less than 10,000 galaxies in this photo, each with as-many-or-more stars as our own Milky Way, and of course each being as mind-bogglingly vast. That all of these clusters could be contained in one insignificant blank patch of sky is a reminder of just how grand the universe is. How minute we, and our entire planet are. How we can’t possibly be alone in the vastness of space, but how we functionally might as well be. To my eyes, this photo is one of the crowning achievements of human discovery, and is quite simply extraordinary.