International literature presents many definitions of megaprojects generally characterized by large-scale, technical and organizational complexity, often with budgets higher than US$1 billion, a lifecycle of decades and major social, political and economic impacts (Flyvbjerg, 2014). Referring to the classical “iron triangle” (time, cost and scope management) many studies give evidence of the low performance of megaprojects management due to the high level of uncertainties these projects needs to face (Eweje, Turner, & Muller, 2012), and that situation reduces also the mega project success. This paper wants to investigate the understanding of megaproject success from the point of view of value management, defining best and proven practices to maximize added value in megaproject value, and so limiting the predominant “iron triangle” perspective (that refer to project management success and not to the project success). The evidence of these opportunities normally emerges only during the project execution phase and is not predictable in the planning phase. Taking stack of these unforeseen opportunities plays an important role in long term success of megaprojects. The research is based on the usage of case studies and interviews that allowed the analysis of the Oil and Gas sector and put the bases for future trends and approaches towards prosperity of megaprojects.