This paper provides an overview of megaproject management, an emerging and costly field. It measures megaprojects in mega, giga, and tera units, indicating a shift to trillion-dollar projects. Global megaproject spending is estimated at USD 6-9 trillion annually, representing 8% of global GDP, making it the largest investment boom in history. Four "sublimes" – political, technological, economic, and aesthetic – explain the increased size and frequency of megaprojects. The "iron law of megaprojects" states that projects consistently over budget, over time, and over and over again. The "break-fix model" of megaproject management is introduced as an explanation for this law. Albert O. Hirschman's theory of the Hiding Hand is critiqued as unfounded and corrupting for megaproject thinking. Megaprojects are subject to "survival of the unfittest," where the worst projects get built instead of the best. The conventional approach to managing megaprojects is reaching a "tension point," where tradition is challenged and reform is emerging.This paper provides an overview of megaproject management, an emerging and costly field. It measures megaprojects in mega, giga, and tera units, indicating a shift to trillion-dollar projects. Global megaproject spending is estimated at USD 6-9 trillion annually, representing 8% of global GDP, making it the largest investment boom in history. Four "sublimes" – political, technological, economic, and aesthetic – explain the increased size and frequency of megaprojects. The "iron law of megaprojects" states that projects consistently over budget, over time, and over and over again. The "break-fix model" of megaproject management is introduced as an explanation for this law. Albert O. Hirschman's theory of the Hiding Hand is critiqued as unfounded and corrupting for megaproject thinking. Megaprojects are subject to "survival of the unfittest," where the worst projects get built instead of the best. The conventional approach to managing megaprojects is reaching a "tension point," where tradition is challenged and reform is emerging.