Throughout history mankind has sought to improve its economic and even its spiritual development through the creation of gargantuan and awe-inspiring infrastructure projects. The twenty-first century has seen the rapid growth of the use of this type of project in providing society’s needs: such projects are widely referred to as “mega-projects”. Mega-projects are extremely large-scale infrastructure projects typically costing more than $1 billion. Mega-projects include power-plant (conventional, nuclear or renewable), oil and gas extraction and processing projects and transport projects such as highways and tunnels, bridges, railways, seaports and even cultural events such as the Olympics. Mega-projects are united by their extreme complexity (both in technical and human terms) and by a long record of poor delivery. What to do in the face of this dilemma is a question that is still being asked by mega-project practitioners and academics alike. This paper presents the unique work of the MEGAPROJECT COST Action which brings together a multi-disciplinary network of over 80 researchers from 24 countries to respond to this dilemma. Mega-project’s aim involves capturing the existing performance of large infrastructural mega-projects and understanding how their delivery can be improved. In order to do this, the investigation has gathered together the MEGAPROJECT Portfolio. The Portfolio contains meta-data on a wide range of mega-projects from across countries and sectors and acts as a firm empirical foundation for the investigation’s activities. Having assembled the MEGAPROJECT Portfolio, this paper shows how analyzing the Portfolio shatters myths of mega-project management and identifies new areas of fruitful investigation. Mega-project’s findings downplay the importance of formal project management tools and techniques in insuring successful delivery. Instead mega-project highlights the need to concentrate on the impact of financing on project governance, the technical modularization of the project and the devastating roles that eternal stakeholders can have on mega-project delivery. Most importantly, it discusses how we can effectively learn across mega-projects in order to maximize their value to their stakeholders and to society as a whole.