![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/0_1746187603941jpeg.jpg\")
A concept design for the X-Seed 4000(Image: Reuben Petty\u00a0\/LINKEDIN)<\/p>\nThe world’s tallest skyscraper would be five times bigger than the unparalleled Burj Khalifa in Dubai if the ‘dream’ proposal created in 1995 ever becomes a reality<\/p>\n
Liam McInerney Content Editor <\/p>\n
04:00, 03 Jan 2026Updated 07:42, 03 Jan 2026<\/p>\n
A concept design for the X-Seed 4000(Image: Reuben Petty\u00a0\/LINKEDIN)<\/p>\n
The world\u2019s tallest current building is the Burj Khalifa<\/a> in Dubai \u2013 but a concept created three decades ago would be five times the height of that if it ever gets built.<\/p>\n The design, which first came to light in 1995, is called the X-Seed 4000, and it would be by far the tallest skyscraper ever made. That\u2019s because it would rise a mind blowing 4km (or 13,123ft\/2.5 miles) into the sky making it just under half the height of Mount Everest<\/a>.<\/p>\n The Japanese construction firm behind it, Taisei Corporation, reportedly wanted it to float on Tokyo<\/a> Bay, and other locations in Asia were considered.<\/p>\n Their hugely ambitious project even proposed to provide homes for between 500,000 and one million people who would live in the 800 floors.<\/p>\n Some 3,000,000 tons of steel would have been required for the complex task and internal air pressure regulations would have been considered for residents to avoid altitude illnesses.<\/p>\n The floating metropolis, stretching 6km wide, was recently discussed on LinkedIn where Reuben Petty provided insight into the dream that never became a reality.<\/p>\n He said: \u201cIts form was inspired by Mount Fuji, featuring a broad, stable base gradually tapering to a majestic peak. This pyramidal shape was not purely aesthetic; it was intended to provide structural stability against the forces of the ocean and potential seismic activity, a significant concern in the Tokyo Bay area.\u201d<\/p>\n The brains behind it hoped it would be a self-contained artificial island supported by floating caissons.<\/p>\n And rather than just be made up of apartments, the vision was for it to act like a city all of its own, with business centres, commercial districts, recreational facilities and research institutions all being on site.<\/p>\n Rumours circulated in 2007 that Taisei intended to follow up with the grand plan, but these were soon put to bed.<\/p>\n George Blinder, managing director of Buildings & Data, claimed at the time: \u201cIt was never meant to be built. The purpose of the plan was to earn some recognition for the firm, and it worked.\u201d<\/p>\n And confirming that the skyscraper was not back on the radar, Shohei Ogawa, a planning manager at Taisei, said X-Seed 4000 was \u201con the shelf now\u201d.<\/p>\n He added: \u201cIt was our dream proposal for the technological advances we thought that could happen in the future.\u201d<\/p>\n One architect and author of a Skyscraper: Vertical Now, Erik Howeler, told Architectural Record<\/a> that it was \u201cpossible\u201d from an engineering perspective to build such a tall building.<\/p>\n However, feasibility wise, he believed the estimated $1 trillion cost would be difficult, along with getting permission to build such a massive structure. He added: \u201cTall buildings create a downdraft at their bases, and cast long shadows.\u201d<\/p>\n![\"Design](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/0_XSeed4000BurjDubaiComparison.jpg\")
It would dwarf the Burj Khalifa which stands at 828 metres (2,717ft) (Image: Newsburst\/Wikipedia)<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/0_Screenshot-2025-12-30-at-131533jpeg.jpg\")
Concepts for the ambitious project (Image: BRIGHT SIDE Series\/Youtube)<\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/0_GettyImages-112295824.jpg\")
The Burj Khalifa is the tallest man made structure in the world(Image: Getty Images)<\/p>\n