There are visionaries right this very minute coming up with buildings designed to house anywhere from tens of thousands of people to, well, entire cities. That is quite interesting. Today let us look at some of these.
All these buildings operate according to the science of arcology, the combination of architecture and ecology. Arcology was first coined by architect Paolo Soleri.
Shimizu Mega-City Pyramid:
Crystal Island is a building project in Moscow, Russia that is planned to have around 2,500,000 square meters (27,000,000 square feet) of floor space and a height of 450 metres (1,476 ft) designed by Norman Foster.
The tent-like superstructure would rise to 450 m, and form a breathable “second skin” and thermal buffer for the main building, shielding the interior spaces from Moscow’s weather. This second skin will be sealed in winter to minimize heat loss, and opened in the summer to naturally cool the interior. The building would be integrated into a new park, which would provide a range of activities throughout the year, with cross country skiing and ice skating in the winter. It is stated to have a multitude of cultural, exhibition, performance, hotel, apartment, retail and office space, as well as an international school for 500 students. The building would be powered by built-in solar panels and wind turbines. The site would also feature on-site renewable and low-carbon energy generation.
The structure called Ziggurat will house nearly one million people and will be self-sustainable with all natural-energy sources. Like the pyramids of the Mayans and Egyptians, this new structure in Dubai is a giant; it will cover 2.3 square kilometers (0.88 square miles) and will be able to sustain a community of up to one million people. The “Ziggurat” is named after the temple towers of the ancientMesopotamian valley, a terraced pyramid structure with successively receding stories. It will be a carbon-neutral structure. 
According to the International Institute for the Urban Environment, the technologies incorporated into the Ziggurat project will make it a viable metropolis. Timelinks has already patented the design and technology used in this project. The building is green and is to be powered by solar, wind and natural sources and is capable of running completely off the grid, according to Timelinks, a Dubai-based pioneering environmental design company who is in charge of this building. The building also boasts an efficient public transportation system that will run horizontally and vertically
The Ultima Tower:
The Ultima Tower is a hypothetical supertall skyscraper, designed by American architect Eugene Tsui in 1991. With a total height of 3,218.7 meters (10,560 ft), the tower would be 2 miles tall, and comprise 500 stories if built. The proposed tower would have a diameter at the base of 1,828.8 meters (6,000 ft), and comprise 1,500,000,000 square feet (140,000,000 m2) of interior floor space. Tsui proposed that the tower would be home to 1 million people, and would cost an estimated US$150 billion. The tower would use the atmospheric pressure difference between the bottom and the top of the tower to create electricity throughout the tower The building is intended to handle problems with overpopulation and to create a “mini-ecosystem” for its inhabitants.
Dubai City Tower:
The Dubai City Tower, also known as the Dubai Vertical City, is a proposed skyscraper design announced on 25 August 2008. The building, created by an architect to display possibly future technologies, is the third tallest building ever fully envisioned after the X-Seed 4000 (4000m) and the Ultima Tower (3217m). If ever constructed, the Dubai City Tower will be much taller than any other current man-made structure, at almost three times the height of the Burj Khalifa. The Dubai City Tower would be almost seven times taller than the Empire State Building.
The design has 400 floors with a 200 km/h (125 mph) vertical bullet train acting as the main elevator. The design is inspired by the Eiffel Tower to better deal with the massive wind forces pushing on it. It has a central core with 6 outer buildings that are connected to the central core every 100 floors. This design both stabilizes the structure and spreads out its mass.
The Bionic Tower:
The Bionic Tower is a proposed vertical city, an extremely large building designed for human habitation designed by Spanish architects Eloy Celaya, Mª Rosa Cervera, and Javier Gómez. It would have a main tower 1,228 metres (4,029 ft) high, with 300 stories housing approximately 100,000 people. The bionic tower would be exactly 400 meters taller than the current tallest building, Burj Khalifa. The point of the Bionic Tower is to use Bionics to solve the world’s rising population problems in an eco-friendly way, an incredibly difficult feat to accomplish.
The Bionic Tower is composed of two complexes put together. The first complex, Bionic Tower, is made up of twelve vertical neighborhoods, each eighty meters high. The neighborhoods are separated by safety areas to make for easier construction and evacuation in case of an emergency. Each neighborhood has two groups of buildings, one on the interior of the building and one on the exterior. Both groups of buildings are situated around large gardens and pools. The second complex, called the Base Island, is 1,000 meters in diameter, and is made up of many buildings, gardens, pools, and communication infrastructures. Foreseen uses of these complexes include hotels, offices, residential, commerce, cultural, sports, and leisure.
BoA (Boston Arcology Building):
Highlights of the Boa:
- It will be capable of housing 15,000 people distributed in hotels, offices, retail, museums, condominiums, and a new city hall.
- The massing of Boa takes its cue from the built environment of Boston proper and as such exudes a rigorous geometric format. That format is further emphasized by the scaling of the golden rectangle whose proportions are: 1: 1.618.
- Within this golden rectangle, Boa’s design alignments have a unique relationship with the Boston common.
What appear to be random projections of massing are actually fashioned as a vertical construct of the “common.” These diagonals are held in check by a fixed border as if a rigid urban edge.
- Because of its scale, Boa is positioned perpendicular to the waterfront, preserving view corridors and general development massing.
- Sky gardens will be inserted into the three main towers every 30 floors. These sky gardens provide landscaped glass enclosed atria. In addition to their practical application of additional sunlit units, the “sky gardens” will create a sense of neighborhood presence and support a range of sustainable initiatives.
Vertical commuting within Boa will be supported by a series of local and express transfer floors.
- Boa is geared to an all pedestrian environment. Accordingly, only select horizontally based areas will be fitted with moving walkways and/or electric train carriers.
- Boa is designed to expand the horizon of sustainability and will seek LEED certification.
- Boa will eliminate the need for cars within the urban structure to create a carbon neutral entity. Some of these elements are secured wind turbines, fresh water recovery and storage systems, passive glazing system, sky garden heating/cooling vents, gray water treatment, solar array banding panels, and harbor based water turbines.
- A massive park system platform (pedestrian only) will be more than double the current green space allocation for the waterfront of Boston.
Boa is a floating city within a city, and is technically feasible, with the method as follows:
The foundation of Boa is a series of poured concrete cells, which are combined to form a buoyant platform. The grid of these cells serves as the foundation for the rigid steel
Hope City, Ghana:
Hope City will host a cluster of buildings and facilities to serve as as an ICT Park. The cluster is expected to cover a total Gross Floor Area of approximately 1,200,000 sqm. It has been designed as a vertical city of towers linked together by bridges at different heights, with both public and private facilities. The cluster is composed of six towers: one tower of 270 m height (75 stories, the highest in Africa), two towers of 216 m height (60 stories) and three towers of 152 m height (42 stories). The towers will have a central space or Piazza on three levels and an inner garden.
Proposed building on the Huan River, Seoul, South Korea:
Here are a series of drawings envisioning arcological buildings:
And another awesome picture: