Ecumenopolis

A **Ecumenopolis** is an urban area which occupies the entire surface area of the planet or moon it is on. The ecumenopolis is the staple of type III civilizations, with every known type-III civilization having at least one.

## **Overview**

Ecumenopolization is the term and action of the form of colonization that turns a celestial body, usually a planet or moon, into an ecumenopolis, which in turn is a city that stretches across the entire celestial body it is located on. This form of colonization is most typically used on selena, desert or ice worlds as they typically do not have life on them for this process to endanger.

Materials used in the process of ecumenoplization are mined from either the celestial body in question, or neighboring bodies such as planets, moons, and asteroids. Though those who are looking to turn a celestial body into an ecumenopolis may use other sources.

Usually this process will begin with the construction of a large dome-like structure that creates an artificial atmosphere with the required or wanted specifications needed for that particular species looking to colonize said body. This isn't always the case as they may not need this to survive.

Due to the process being rather expensive on both resources, or funds if the particular civilization uses currency, this process is usually not used. Instead, terraforming is favored over it however this isn't always the case as a celestial body may lack the requirements to be terraformed in the way the would be colonizer needs it to be.

## **Design**

These cities are typically built in layers, with the bottom layer on the surface of the planet. Each layer is usually over a kilometer apart from the layer above and below it. These cities typically have well over 100 layers each, with some of the largest ecumenopoli having over one hundred and fifty layers. These cities have trillions of construction drones milling along the vast support network, filling in any cracks or fissures as they go.

Any oceans that exist on the surface of the planet are either polluted to the point of being useless or completely gone, used for drinking water by the vast populations. If the oceans are still there, they are buried under many layers, with a complex system of catwalks above them.

An ecumenopolis is usually devoid of any meaningful amount of plant life, so oxygen has to be synthesized artificially. Every ecumenopolis either creates oxygen via electrolysis of water or using cyanobacteria. A city like this goes through more oxygen a year than there was oxygen on most terrestrial planets, which means that the planet needs to produce a ludicrous amount of oxygen.

The city requires exorbitant amounts of energy. This energy is used for a number of things, such as transportation, feeding the population, and waste disposal. The waste heat of an ecumenopolis from these activities is very great, so great that it would make the planet uninhabitable of the problem weren't addressed. An ecumenopolis usually has a radiation network on its surface. This network is a high-surface-area metal which is able to radiate the waste heat into space. It is best described as a massive heatsink for the entire planet.

Thanks to their nature, ecumenopolis worlds can hold extremely large populations of trillions of individuals or more, as the largest of these cities can have well over a quadrillion residents.

The lower layers of every ecumenopolis are always worse, with some being inhospitable. The bottom layers of most ecumenopoli are polluted to the point of being absolutely toxic to most forms of life. The upper layers are much better, with property on the highest levels costing much more than the property on the lower to middle levels.