The concept of the Citadel for bitcoiners was probably launched in this 2013 ‘Time traveler from the future’ eessay, warning us plebs to stop this new black hole experiment called Bitcoin

https://telegra.ph/CITADEL-I-am-a-time-traveler-from-the-future-here-to-beg-you-to-stop-what-you-are-doing-04-20