The towers were designed by Argentine American architect César Pelli. They chose a distinctive postmodern style to create a 21st-century icon for Kuala Lumpur. Planning on the Petronas Towers started on 1 January 1992 and included rigorous tests and simulations of wind and structural loads on the design. Seven years of construction followed, beginning on 1 March 1993 with the excavation, which involved moving 500 truckloads of earth every night to dig down 30 metres (98 ft) below the surface.