Millennium Tower Tokyo
Foster + Partners designed an 840-metre vertical city for Tokyo Bay that would house 60,000 people offshore.
Quick facts
- Existence state
- Never Born
- Peak stage
- detailed preproduction
- Research confidence
- high
- Last verified
What it was
A proposed self-contained megatower in Tokyo Bay designed for the Obayashi Corporation.
The conical structure organised transport, homes, offices and services as a vertical city protected from extreme winds. It was developed as a serious engineering and architectural study during Japan's asset boom.
Existence timeline
Obayashi asks Foster + Partners to explore a giant offshore vertical city.
A tapered, braced tower is developed for severe wind and seismic conditions.
Housing, work, services and internal transport are organised for tens of thousands.
Japan's asset-price collapse undermines the context for megaproject delivery.
The project remains a design study rather than a construction programme.
Why it ended
The economic conditions that supported giant speculative visions collapsed and the tower did not proceed to approval or construction.
Last confirmed trace
Foster + Partners preserves drawings, sectional studies and project descriptions.
What it left behind
The tower became a reference point for vertical-city design and for the extraordinary scale of late-1980s Japanese construction speculation.
How we classified it
The proposed archive unit never reached ordinary public access in the form being documented.
The strongest verified milestone maps to detailed_preproduction under Arrival Score V1.
Sources & verification
Last reviewed 2026-08-01. Sources are linked so readers can inspect the evidence directly.