*This article is based on information as of February 2026.

1. The Rise of Megastructures: Japan's Metabolism and the 1960 Tokyo Plan

An "extreme prescription" for rapid urban expansion

In fact, it was none other than Japan that the revolutionary concept of megastructures first emerged onto the global architectural history stage. Having recovered from the ruins of World War II, Japan was on the verge of being engulfed in a wave of rapid economic growth and the accompanying explosive population growth. In particular, the capital, Tokyo, saw an influx of labor from all over the country, and in the blink of an eye, it expanded abnormally to become a city of 10 million people. This resulted in chronic traffic congestion, a serious housing shortage, and a deterioration in the living environment, and the limitations of traditional urban planning, which simply involved expanding flatly, were clearly apparent to everyone.

Against this unprecedented backdrop of a sense of crisis regarding urban infrastructure, a Japanese architectural movement called "Metabolism" was formed from the late 1950s to 1960, centered around young architects such as Kurokawa Kisho, Kikutake Kiyonori, and Maki Fumihiko. Metabolism is a biological term meaning "metabolism." These architects fundamentally rejected the rigid and fixed concepts of conventional cities and architecture, and instead likened the city to a living organism. They established the groundbreaking idea of allowing the city itself to self-replicate and renew itself by clearly separating and combining a "solid, unchanging main infrastructure (skeleton) that can withstand hundreds of years" from "habitable modules (cells) that can be freely replaced in line with growth and the changing times."

It is worth noting that they published a manifesto, "METABOLISM/1960: Proposals for Cities," in which they presented a series of ideas that overturned conventional wisdom, including Kikutake Kiyonori's "Ocean City," around the time of the World Design Congress held in Tokyo in 1960. This became a powerful fuse that sparked the debate over megastructures in the global architectural world.

Kenzo Tange's "Tokyo Plan 1960" shocked the world

Furthermore, Kenzo Tange, a spiritual pillar of the Metabolist movement and a master of Japanese architecture at the time, published "A Plan for Tokyo, 1960" in 1960, which had an immeasurable impact on urban planners around the world.

Tange flatly rejected Tokyo's overcrowded "centripetal radial structure," in which all functions and transportation are concentrated toward a single point in the city center. Instead of expanding the land area by filling in Tokyo Bay, he presented a groundbreaking vision of constructing a gigantic "linear city (civic axis)" stretching approximately 18km across the waters of Tokyo Bay itself. This was the ultimate megastructure concept, with a gigantic offshore megastructure at its core capable of accommodating and handling a population of approximately 5 million people, on top of the existing population of approximately 10 million.

As a result, while the megastructure concepts of the time, including the "Tokyo Plan 1960," were extremely forward-thinking in anticipation of the arrival of full-scale motorization (car society), they were hampered by the limitations of the architectural technology of the time and the enormous, astronomical construction costs, and were never completed as actual cities.However, the philosophy of "modularizing urban functions" and "ultra-concentrating infrastructure" never disappeared, and continues to leave a significant legacy in the history of urban planning around the world, and even in modern-day smart city concepts.

2. Comparative data on the scale of megaprojects and contemporary trends

To accurately grasp the extraordinary scale of megastructures, it is essential to compare them using quantitative and visual data. Here, we compare the historical Japanese project "Tokyo Plan 1960" with the current national project "The Line" in the Middle East.

The tables and graphs below can be scrolled horizontally (swipe) for easy viewing on small screens such as smartphones. Follow the dashed lines between the cells to see the overwhelming difference in scale and how they compare with the construction market as a whole.

[Graph Commentary] Runaway Construction Costs and Japan's Market Size

The biggest obstacle to realizing a megastructure as a real city is always the astronomical construction cost. The sheer unrealistic scale of the budget for "The Line" becomes clear when comparing the US dollar-based estimates given in major media reports with the size of Japan's entire construction market, which serves as a reference point.

3. The Light and Dark Side of Modern Mega-Projects

It's now 2021, about 60 years since the idea first came about in Japan. Backed by abundant oil money and a national strategy called "Vision 2030" that aims to break away from oil dependency, Saudi Arabia has unveiled to the world the modern megastructure "NEOM" project, and in particular the linear city at its core, "The Line."

Measuring 170km in length, 200m in width, and 500m in height—higher than the Empire State Building—NEOM officially announces that its massive mirrored walls will house up to 9 million people, run on 100% renewable energy, and completely eliminate roads and cars, making it the ultimate concept straight out of a science fiction movie. However, while this approach of forcibly cramming all urban functions into a single gigantic structure promises dramatic benefits, it also carries serious risks and side effects on a scale never before experienced by humanity. Below, we will compare and contrast the "lights" and "shadows" of this vision.

A crucial difference from similar urban planning concepts

In modern urban development, megastructures are often confused with other cutting-edge urban concepts. Although they share the same goal of streamlining and consolidating urban functions, there are crucial differences in their approaches (physical or political, and nature or technology).

• Arcology:A fusion of architecture and ecology. Whereas megastructures pursue the limits of technology and enormous size, arcologies prioritize compactness as a means of "returning the land to nature," with harmony with the ecosystem as their primary goal.
• Compact City:Rather than building new megastructures, we will reorganize the layout of functions within the existing urban center and infrastructure. This is an extremely realistic approach that controls residential density through "software and policy guidance" such as legal regulations and zoning (designation of use areas).
• Smart City:This is a data-driven urban model that optimizes infrastructure operations by spreading information and communication technologies such as IoT sensors and digital twins throughout the city while maintaining existing street spaces, regardless of the shape or physical size of the buildings.

4. Possibilities in local cities: "Local Arcology" in Toyako Town, Hokkaido

As we have seen, it is obviously unrealistic to construct a gigantic megastructure in a regional Japanese city, which would require astronomical funding and place a huge burden on the natural environment. As major news reports have shown, even national projects funded by huge amounts of oil money have been forced to revise their resident targets downward, and the totalitarian development model of "cramming everything into a single giant box" is already running into a wall of reality.

However, we must not stop thinking here. The concepts underlying megastructures - "ultra-concentration of infrastructure (compactness)," "three-dimensional construction to reduce the burden on the natural environment," and "modularization of functions (metabolism)" - are not wrong in themselves. In fact, they can serve as a powerful compass for sustainable urban development for the next generation, especially in Japan's regional areas, which face harsh natural environments and serious population declines. Here, we will explore Toyako Town in Hokkaido as a model case.

Population decline and snow removal costs challenge the limits of decentralized infrastructure

Toyako Town and many other Hokkaido municipalities are facing a serious demographic winter, characterized by an outflow of working-age population and a declining birthrate. Despite a continuing decline in population and tax revenue, the continued imposition of huge costs on widespread snow removal, road pavement repairs, and long-distance maintenance of water and sewer lines in "wide, thinly dispersed residential areas" that were developed in a disorderly manner during the past booming era, mathematically spells certain financial collapse for the local government.

As residents move out due to the difficulty of living there, the number of vacant houses and abandoned farmland scattered around the area increases, and the burden of maintaining the infrastructure falls heavily on the few remaining residents, creating a negative spiral. Furthermore, the area is home to Mount Usu, an active volcano with a history of repeated eruptions, and in an environment where unique natural threats coexist side by side, there is a constant demand, even in peacetime, for "robust disaster prevention shelter functions" that can quickly protect the lives of residents and tourists in emergencies.

A miniature megastructure concept based on "selection and concentration" of tourism revenue

On the other hand, Toyako Town has enormous potential that is not found in other regions. According to publicly available tourism statistics, the number of overnight guests in the town in fiscal year 2024 is expected to reach 645,881, and when multiplied by the average spending per tourist of 70,114 yen, the total annual tourism spending will reach approximately 45.3 billion yen. This is an extremely strong foreign currency earning potential for a local municipality.

Rather than using this abundant cash flow aimlessly to extend the life of scattered aging infrastructure, we should concentrate investment to the maximum extent possible in safe central areas with low risk on the hazard map. Specifically, we should integrate town halls, hospitals, commercial facilities, highly insulated modular housing, and emergency shelter functions into a single "medium-sized three-dimensional structure (complex).""Local Arcology (Miniature Megastructure)"This is an implementation of.

Completely indoor settlements and "rewilding"

During Hokkaido's harsh winters, the biggest obstacles for both the government and residents are the heavy work of snow removal and the enormous amount of heating energy required. By consolidating the town's main functions into a single three-dimensional structure and moving corridors and shared spaces indoors (or creating an all-weather arcade dome, for example), the risk of elderly people falling while moving around in winter and the life-threatening struggle of shoveling snow can be completely eliminated. At the same time, by creating a microgrid within the facility and using local resources (renewable energy) such as abundant hot spring heat and geothermal heat to heat the entire building, the ultimate eco-city can be realized, free from reliance on external fossil fuels.

The most important aspect of this concept is to encourage residents to move to multi-story, centrally-located facilities (compact cities), and then have local governments gradually purchase vacant houses and abandoned farmland in the suburbs, demolish the buildings, and return the land to its former forests and farmland (rewilding). The concept minimizes the physical footprint of infrastructure that humans must manage and maintain, allowing people to live safely and comfortably in high-density, high-tech settlements, while enjoying the scenery of vast, untouched nature. This is precisely what a new Hokkaido-style residential model looks like, translating the philosophy of megastructures to a local scale.

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