From the Internet Mapping Project, a long term project to track the growth of the Internet and its subnetworks.
How this was made: At Bell Labs, Ches modified a hacker trick and sent a storm of IP packets out randomly across the network. Each packet was programmed to self-destruct after a delay, and when this happens, the packet failure notice reports back the path the packet took before it died. To visualize this sea of data, Ches applied place & route software from the semiconductor CAD industry to untangle the hairball of links and spread them out in a 2D map that humans can easily absorb. When this is done from within a corporate network, one can find security gaps and unknown network connections. (disclosure: we invested them when they spun out of Bell Labs)
Here is a gallery of Internet maps by Ches of Lumeta.
This technique can also see the network “lights go out” during wartime bombing raids.