Il costo dell’Alta Velocità ferroviaria in Italia - Cost overruns are common in large and complex projects, especially in high speed rail ones. Budgeting for cost escalation is a major issue in the planning phase of these projects. This paper describes lessons learned on high speed rail in Italy and focuses on problems such as initial poor design, tactical budgeting, inadequate cost estimation and risk assessment, etc. The paper discusses possible means to avoid major flaws in the initial conceptual design of mega-projects. There is a growing understanding of the need to focus on the front-end phase in order to achieve more successful and cost-effective projects.