This paper highlights the construction methodology and engineering design of the support systems for Mobility and Spiral tunnels of NEOM’s company’s Cube Mountain project in the Gulf of Aqaba (GoA). The Cube Mountain project is the construction of a building inside an open excavation by the top-down method, located in the mountainous region near the coast. To implement this Project, in the month of November 2023, construction of the Mobility tunnel of 258 m length was started, and in the month of March 2024, construction of the Spiral tunnel of 650 m length was started to reach the elevation of 140 m from mean sea level to construct a platform for the raise boring drilling activity. The drill and blast method had been used to construct these two tunnels. Concepts of these two tunnels and portal slope, properties of supports and reinforcement, constructions of portal slope, initial reach of portal, and false portal have been discussed in this study. Shotcrete operation, rock bolt installation and steel rib installation are used to improve the support system. This study presents concepts on the design of tunnel highlighting difficult boundary conditions. Design approach using Q-system and calculations of the required length of rock bolt have been made in this work. Support systems had been designed in this project using empirical method and recommendations are made regarding the supporting system of both Mobility and Spiral tunnels for the six classes of rock mass.