The number of megacities – urban areas with populations of at least 10 million – rose from eight in 1975 to 33 in 2025. By 2050, Dhaka’s population could reach 52.1 million and Jakarta’s 51.8 million. Depending on the global demographic and socioeconomic scenario, Lagos could have anywhere from 61 million to more than 100 million residents. And a city of 100 million is no longer merely a megacity. The Burj Khalifa remains the world’s tallest completed building at 828 metres, but construction of the Jeddah Tower has resumed.