Pavilion Bukit Jalil Mall is a new high-end commercial development located in Bukit Jalil, Kuala Lumpur, Malaysia. The main attraction of the mall is the piazza, an external event space covered by the Mega Canopy, a 115m span and 20 to 40m high freeform steel roof covered with ETFE, supporting fans, lights and exhibits and providing an aerated and impressive 80m to 100m column-free space for the visitors. Although complex, the geometry was generated to fully take into account the buildability and to facilitate the fabrication of the ETFE. Many services run on the structure - such as lighting cables, winches cables or fans cables. The structure was designed so that all the cables could be fully concealed within the columns and above the main arches to keep the services out of sight. Challenging supporting conditions made the structure highly prone to buckling and sway. Optimization of the columns layout and height enabled to reduce the sensitivity of the structure to buckling while keeping an elegant and lightweight structure.