This chapter aims to share the main health and safety practical lessons retrieved from the underground excavation and final lining stages of the 2nd phase of the Marão Tunnel ("MT") construction. This is the longest tunnel built in the Iberian Peninsula in recent years and its excavation has been interrupted for three years, only with primary support applied in the excavated areas. First, the case study is presented. Afterwards, the lessons learnt when dealing with the usual main risks in underground works (run-overs, falling blocks, burying, untimely blasts, fall from heights and gases and dust inhalation, among others) are described. Adding to these were the specific conditions of this particular work, some of which stemmed directly from the suspension of the works. This paper pretends to be a legacy for the health and safety in the construction industry since it presents a successful example of risk management using new approaches.