Saudi Arabia's $1 Trillion Skyscraper

construction engineering smart city skyscraper mega construction saudi arabia top luxury massive builds megaprojects buildings the line neom biggest skyscraper mirror line 1 trillion skyscraper saudi arabia mirror line futuristic city future city biggest megaproject in history most expensive construction project most expensive megaproject biggest construction project world's largest megaproject saudi arabia neom saudi arabia vision 2030 no car city