Multiple outlets report on the X-Seed 4000, a long-standing concept design for what would have been the world’s tallest skyscraper. The proposal is described as dwarfing Dubai’s Burj Khalifa, which is widely cited as the current tallest building. According to the reports, the X-Seed 4000 concept would rise to around 4,000 meters (about 2.5 miles) and be structured across roughly 800 floors. The concept is also presented as a large-scale residential development: it is said to be designed to house up to one million residents. One source notes that the concept was unveiled about three decades ago but was never developed or built, meaning it remains a design study rather than an active construction project. Overall, the coverage focuses on the scale of the proposed height and population capacity, while providing limited additional detail about feasibility, backing developers, or any formal plans to move forward.