XKCD is a favorite geek comic and from time to time, it dabbles in whatever web technology or controversy is popular at the time. At different times though, it pushes beyond its simple stick man aesthetics and uses modern web technologies to great effect.
Today's comic is one of those times. The comic is titled "Click and Drag" and for good reason. You only get to see a small area of it at any given time, about as much as three standard panels, the drawing itself being huge.
Huge doesn't even begin to cover it, it's several miles wide and tall, at scale. It's made up of huge 2048x2048 PNGs and there are over 100 of them, but you wouldn't know it since moving around, by clicking and dragging, is smooth and continuous.
The idea behind the comic is to make you appreciate just how big the world is, by showing you what can fit in 4-mile radius.
And there are a lot of details, there are so many Easter Eggs, it's tough to call them Easter Eggs anymore. You'll find the entire Super Mario 1-1 level, X-Wings, a Minecraft Creeper, William and Kate, Waldo and so on and so forth.
The best way to enjoy it is to just dig into it. However, if you want to check out its scale, you can see the entire thing, scaled down here. Alternatively, you can go here and have an easier time navigating it all.