There are thirteen pillars upholding the critical national infrastructure (CNI) that allows for the every day running of our society. These pillars are sectors that rely on four generations of operational technology (OT) systems with the oldest generation being pre-Internet. What are these industrial control systems (ICS) that we rely on, and how are they vulnerable? This talk will outline a generic ICS from the hardware to the protocols that allow the complex systems to speak with one another. Research into these systems is often done on physical testbeds and digital twins (I don't know about you, but I wouldn't want to try hack an actual nuclear reactor). The talk will discuss the testbeds that I'm lucky enough to play with day-to-day. How are these industrial control systems vulnerable, and what can we do to protect these systems from malicious actors? Finally, how are these thirteen pillars connected? If we knock one down, will the others fall like dominos?