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This article is for the PC version of Stellaris only.
Humanoid Empire constructing a Dyson Sphere
Note: Ringworlds can be restored even without Utopia enabled.

Megastructures are colossal object constructions. Expensive and time-consuming, these remarkable feats of engineering are nonetheless important wonders that provide large bonuses, demonstrating the technological and economical primacy of the builders' empire.

It is possible to find ruined megastructures spread in the galaxy to repair and restore them into their final form. Doing so allows saving a lot of the resources required to construct them. While restoring the megastructures does not require any Ap slot available.png ascension perks, it does require the player having researched the technology Tech mega engineering.png Mega Engineering.

There are two types of megastructures. Habitable projects and Galactic Wonders. Galactic Wonders provide massive bonuses and cannot be destroyed by any crisis but are limited to one per empire. They also have a different texture depending on the empire that built them.

It is only possible to build, upgrade, or restore one megastructure at a time, except in the case of habitats.

Ascension Perks

A number of Ascension Perks enable or affect the building of Megastructures.


This Perk enables the building of Habitats. It has significantly lower requirements than the perk for the other Megastructures, requiring only some of the prerequisites of Tech mega engineering.png Mega Engineering rather than the tech itself.

Galactic Wonders

Requires Tech mega engineering.png Mega Engineering and three previous ascension perks. Enables the Dyson Sphere, Science Nexus and Sentry Array. What each of these Megastructures have in common is that they provide effects and bonuses without any of the disadvantages associated with a colonized planet and their presence in a system is not incompatible with habitats.

Circle of Life

Requires Tech mega engineering.png Mega Engineering, Voidborne Voidborne and three previous ascension perks. Enables the construction of Ringworlds. They offer extreme living space at higher efficiency than Habitats. However the system they are built in must be devoid of habitable planets as in the construction of the ringworld all planets will be destroyed to supply the materials. You can build an infinite number of these.

Master Builders

Master Builders Master Builders will increase the buildspeed of Megastructures by +100%. It requires Tech zero point power.png Zero Point Power and instantly unlocks Tech mega engineering.png Mega Engineering if not unlocked already.


Mammalian habitat.

An artificial planet in all but name, these Habitats offer 12 tiles to work coupled with 100% Mod habitability.png habitability for all species. Its appearance is dependent on the builders' empire appearance. The constructed habitat still requires colonization but colonizing them is free.

Habitats have a unique set of buildings distinct from normal planetary ones. This set of buildings has good Energy Credits.png Energy and Research.png research yields, but is less effective for generating Food.png Food and Minerals.png Minerals. Gene Clinics, tradition and Horizon Signal buildings can also be constructed.

The project takes 5 years to complete and costs a total of 150 Influence.png influence and 5000 Minerals.png minerals.

Requires the Voidborne Voidborne ascension perk, which does not require Mega Engineering, only the Battleship and Fortress technologies. It cannot be built on habitable planets, asteroids, moons or planets with an anomaly.

While habitats cannot be destroyed by normal empires there is a war demand to disassemble them.


Habitats have considerable production penalties for both Minerals and Unity, as they effectively act as a rather small planet. However, they offer superior Energy and Science income, while doubling as an Orbital Farm. They also require considerably less micromanagement, because none of the buildings need upgrades nor provide adjacency bonuses. Of all the megastructures, they have the least onerous requirements in terms of technology and placement.

Habitats are uninhabited when they are built and need to be colonized although this does not require influence like planets do. They will also inherit orbital tile deposits from their orbiting planet.

If a habitat is disassembled, it will strangely never be possible to build another habitat, or even a mining/research station, orbiting the planet, so any strategic resource on the planet is permanently lost. What's more, habitats can't have spaceports, so if an empire has only habitats and no planets, it will never be able to build ships.


Ring world.

Immense in both radius and scope, these Ringworlds encircle their system's sun and award their owner four 25 tile sized sections when fully constructed. Its carefully designed ecosystem and finely-tuned atmosphere offer perfect living conditions towards all residing species, giving them 100% Mod habitability.png habitability on the ringworld.

The project takes 58⅓ years to complete and costs a grand total of 300 Influence.png influence and 110 000 Minerals.png minerals. With the Ap master builders.png Master Builder ascension perk it takes 29⅙ years instead. However, because each section is built separately after the completion of the frame, the Ringworld can be a valuable and productive asset long before its completion.

The initial site is built by a construction ship around the star, and cannot be begun if another construction ship is building a megastructure or if the system contains habitable planets. Once the site is complete, it constructs the subsequent sections without the need for a construction ship.

Ringworlds cannot be built around black holes. All planets in the system are consumed upon the completion of one of its frame.

Requires the Ap the circle of life.png The Circle of Life ascension perk. The following list shows the upgrade order.

Type Upkeep Time Cost
Ring World Site.png Site -5 Energy Credits.png 1 800 Time 300 Influence.png
10 000 Minerals.png
Ringworld frame.png Frame None 4 800 Time 20 000 Minerals.png
Ring World Habitable.png Completed Section None 3 600 Time 20 000 Minerals.png


The Ringworld offers a massive amount of living space (100) while only counting as 4 Planets. The big limitation is that there are only very few Systems one can build them in, as the system requirements are identical to the ones for a Dyson Sphere, except it also needs a lot of planets to be used for raw material. Like Habitats it also requires a separate Ascension Perk from the other Megastructures. It is the only Megastructure that is exclusive for its system, as its creation will consume all other stellar bodies in the system.

Construction Events

The following events can take place while constructing a Ringworld:

  • Favorable leadership conditions increase the building speed by 20%.
  • A mineral deposit is discovered and you are given the option to halt construction for 20 days to get 500 Minerals.png minerals or proceed with the schedule.
  • A number of workers might go missing, delaying the construction for a month. Two months later it will be revealed that one of the planets used in the construction had a species of furry worms the workers have grown fond of. You are given the option to either exterminate them and delay construction for a month or allow them on the building site. Whatever choice is made a month later the worms will be found feeding on the missing workers underground and be exterminated.
  • Another empire might contact you, thinking that you are making weapons of mass destruction on your ring world. They will want to inspect the ring world. If you accept the request the construction will be halted and the empire gets the "Request Accepted" opinion modifier (+40 Diplomacy opinion.png opinion, -2 yearly). If you declined they get the "Request refused" modifier.

Conquerable Ringworlds

Up to 7 Ringworlds can spawn "naturally" in a game in various states. Damaged segments can be repaired with the Tech mega engineering.png mega-engineering tech.

  • 1 in the Sanctuary system. All 4 habitable sections are intact and each contains one pre-FTL civilization, none advanced beyond Steam Age. The system was abandoned by an Enigmatic Observer Fallen Empire but contains automated defense platforms totaling over 50k Fleet Power.
  • 3 in the systems of the Ancient caretakers (if Synthetic Dawn is installed) or Keepers of Knowledge (if Synthetic Dawn is not installed). The ringworld in the home system has 3 intact and one ruined section while the other two ringworlds are completely ruined and require each section to be repaired separately.
  • 1 in Cybrex Alpha. It requires completing the Cybrex precursor event chain. The ringworld is completely ruined and requires repairs on each section.
  • 1 in Cybrex Beta. The system will only be revealed if the Contingency sterilizes 20% of the galaxy. A short time after the Contingency is defeated the Cybrex will leave the galaxy, leaving the ringworld free for the taking.
  • 1 in a random empty system if Utopia is installed. It is completely ruined and each section requires repair.

Galactic Wonders

These megastructures require the Galactic Wonders Galactic Wonders ascension perk and can only be built once per empire. However their bonuses are massive and they cannot be destroyed, only captured. Habitats can also be built in the same system as Galactic Wonders. Each Galactic Wonder starts with a construction site costs 300 Influence.png influence and 10 000 Minerals.png minerals and provides no benefit. However each subsequent construction phase will bring increasing bonuses, culminating with the end of the megastructure construction.

Galactic Wonders conquered from other empires do not count against the build limit. Nor do ruined ones that are found and repaired.

Dyson Sphere

Dyson Sphere.

These multi-staged, truncated icosahedron-shaped structures harness the energy output of an entire star. A fully constructed Dyson Sphere provides a whopping +1000 Energy Credits.png energy.

All rocky planets and moons in the system turn into frozen or cold barren worlds upon its completion due to the lack of thermal radiation they would receive considering the star has been mostly completely encased.

The project takes 55 years to complete and costs a grand total of 300 Influence.png influence and 260 000 Minerals.png minerals. The following list shows the upgrade order.

Note: The amount of Energy Credits.png energy provided does not vary between different star types.

Type Produces Upkeep Time Cost
Dyson Sphere Site.jpg Site None -5 Energy Credits.png 1 800 Time 300 Influence.png
10 000 Minerals.png
Dyson Sphere Frame.jpg Frame None None 3 600 Time 50 000 Minerals.png
Dyson Sphere Partial (25%).jpg Partial (25%) +250 Energy Credits.png None 3 600 Time 50 000 Minerals.png
Dyson Sphere Partial (50%).jpg Partial (50%) +500 Energy Credits.png None 3 600 Time 50 000 Minerals.png
Dyson Sphere Partial (75%).jpg Partial (75%) +750 Energy Credits.png None 3 600 Time 50 000 Minerals.png
Dyson Sphere.jpg Dyson Sphere +1000 Energy Credits.png None 3 600 Time 50 000 Minerals.png


During the construction of the framework of the sphere, neighboring empires may tell you their astonishment about your progress in constructing the sphere and request for your permission to allow a group of engineers to study the technology. Accepting the request may result in opinion improvement by 40 which decreases by -2 yearly. You will also be awarded 250 points of engineering research. There is no clue that whether the empire will be able to construct Dyson Spheres after the event.

Once you finish the framework of the Sphere, there is a chance where a neighboring empire will approach you revealing the importance of that star in said empires culture and asking for either a formal apology or a donation of credits. Refusing adds "The Blind Wanderer" to their opinion screen which reduces their opinion of you by -40 which decreases by +2 yearly.


The Dyson Sphere offers a massive energy income at no cost for Unity or Research from population/colonized planets. Habitats may also be built in systems with a Dyson sphere, but not other megastructures.

Science Nexus

Completed Science Nexus

The Science Nexus takes close to 25 years to complete and costs a grand total of 300 Influence.png influence and 100 000 Minerals.png minerals and provides a spectacular +225 Research.png research bonus across all fields.


The Science Nexus provides a huge bonus to Science without any penalty from having another colonized planet. The initial site cost 10,000 minerals, and the three stages after cost 30,000 minerals each while providing 75/150/225 to all science. Even the first stage is equivalent of a research-focused planet.


One of these events can take place while owning a Science Nexus that is completed or has its research wings built.

  • An incident at the physics department made everyone black out for 15 minutes and the scientist leader handling it disappeared. One year later the leader will mysteriously reappear as if nothing happened and gain the Leader trait lightbulb on.png spark of genius and Leader trait maniacal.png maniacal traits.
  • A neural bank using brain power to improve research speed is invented. Only one of your scientist leaders will volunteer and allowing it will remove him or her from your pool but add a permanent +25 Research.png research production to the science nexus.
  • Fountain of Youth: You might be given the option to recruit a prominent expert in the field of life-extension for 1000 Energy Credits.png energy credits or focus on research on organic supercomputers for free. Recruiting the scientist will lead the organic engineering chief scientist to accuse him of being a fraud and demand an investigation that will cost 500 Energy Credits.png energy credits. If the demand is refused two months later it will be revealed that her suspicions were right as the "prominent expert" disappears and you will gain nothing. Starting an investigation will give you the option to either apprehend him and gain a small amount of Society Research society research or market his fake research and gain the Fountain of Gold modifier for a year, giving you +200 monthly Energy Credits.png energy credits for a year. Focusing on organic supercomputers instead it will lead to the aforementioned neural vault event (which can happen individually as well).

Sentry Array

Completed Sentry Array

The easiest Galactic Wonder to construct, a Sentry Array must be built around a star or black hole and takes 25 years to complete and costs a grand total of 300 Influence.png influence and 90 000 Minerals.png minerals.


The completely finished Sentry Array will give you vision over the entire galaxy. This makes it an important military and strategic asset, as complete intelligence of every pop and fleet in the galaxy can give considerable strategic information. On lower levels it will still provide at least considerable vision, quickly eliminating any "blind spots" in the sensor coverage of the player or their federation.

Provided you do not lose the system hosting your Sentry Array, it makes the Planetary Signal Booster technology useless, allowing you to focus on other late-game repeatable technologies. Due to their shared importance the capital system is usually an ideal location for the Sentry Array. On tiny galaxies even a halfway built Sentry Array will give complete coverage.

Ruined Galactic Wonders

Ruined Dyson Sphere

One of each Galactic Wonder can be found ruined in the galaxy, and the largest galaxies can spawn two or even all three ruined Galactic Wonders. Repairing them only requires Tech mega engineering.png mega-engineering technology and no Ascension Perk, while also granting a better chance (x20 weight) to draw Tech mega engineering.png mega-engineering. While they upgrade from their broken to a fully functional state in one step, they do not count for any achievements and generally do not trigger any of the special quests associatied with them. However as they do not count for the achievements they also do not count against any limit for that particular megastructure.

Ruined Megastructure Time Time Minerals.png Minerals
Dyson Sphere 7200 50000
Science Nexus 3600 30000
Sentry Array 3600 30000

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