Author's Note: So thanks to Clown2107 for the suggestion for the contents of this article. Read, Review, Favourite and Enjoy!
Spectre Padok Wiks here, With compilation on Union technology. For now will be covering Union Megastructures, exact details of construction are largely classified and better covered in individual files if I ever get the chance, for now will be lumping them together into one file since don't know when will be sending next report, or this one for that matter. Megastructures is a catch-all term for simply massive structures too large too every properly fit onto a planet. To give you some idea of what I mean by this...
Citadel/Mass Relays
Let's get this out of the way, the most well known Megastructure is the Citadel, a massive space station believed to be built by the Protheans to act as a central control unit for the Relays and the Mass Relays which are massive galactic mass drivers designed to transport ships across the galaxy, by the standards of the Union the Citadel is considered a small sized Megastructure five wards in size. The Lich Necropsy however claims that both the Citadel and the Mass Relays are even older than the Protheans are. Do not need to go into detail about these two, but rather mention them in order to give a sense of scale to other Megastructures mentioned shortly. Now for the Meat of the discussion.
Gateway
Another Small Megastructure is the Gateway, based on research into various naturally occurring worm holes the Gateway fulfils much the same role in the union as the Mass Relays do in Citadel space, chief differences being that the gateways are far less durable than the Mass Relays and do not have a centralised governing centre IE the Citadel. This partly necessitates that a small armed fleet is required to be maintained around a given Gateway. A Gateway is located in the Eden System and apparently took 3 years to build, from what I understand it's mostly used to transport crops.
Habitat
Considered to be a small Mega structure, roughly the size of a city, Habitats are built in orbit around planets or inhabited moons. Connecting back down the surface via Space Elevator the Habitat is both home for those who live there and off world storage. I myself live close enough to the elevator that I was able to visit the habitat during the recent galactic holiday. I had a lovely Dinner called Spaghetti, more information in my dossier on Union foodstuffs, and proceeded to acquire a indepth wealth of knowledge concerning potential habitat installations. Currently the Habitat is considered to be small sized, a mere four cities or, to go back to the Citadel Metaphor from before Wards, large. A two stage expansion plan taking place over sixty six Galactic standard months will expand the habitat to six and eight respectively. For a dedicated agri-world like Eden Prime, this mega structure project is praise worthy, and will open up even more space down below for agriculture. Personally I like the homestead and do not plan to move.
Orbital Ring
Aside from Habitats, plans also in place to construct Orbital ring around the Eden planets further enhancing potential habitability of the planets. Ringworld's are classified as mid sized mega structures, as the name implies they are designed to be built around the planet in question. Will take little under three Galactic standard years to finish building, once complete will be possible to house four ward sized modules, two specialised buildings and six separate platforms simultaneously. To give a idea behind the diversification in play here:
*Habitation Module: City
*Orbital Shipyard: Designed to house one ship at a time, requires specialised building planet side known as orbital assembly complex, as it will be coming up many times will abbreviate to OAC
*Orbital Anchorage: Fleet Anchorage and Naval office, ships can dock but not be worked on, requires OAC.
*Planetary Defence Guns: Two slots for medium weapons platform, will work on separate file, requires OAC. Should check if Eden Prime has one.
*Planetary Defence Battery: Two slots for Missile weapons platform, will work on separate file, requires OAC.
*Planetary Defence Hangars: Hanger for strike craft, intend to cover in file about strike craft requires OAC.
Aside from five aforementioned modules there are also room enough for two specialised building types, of which there are 12 available.
*Climate optimisation Stations: Or in less words, weather machines. Capable of optimising crop yields, will most likely see installation on the ring world.
*Low Gravity Mega Refinerys: Ore Processing centres.
*Alloy Procession Facilities: Self Explanatory.
*Stratospheric Ionizers: Improves the electrical grid of the planet below, less energy waste in the process.
*Giga Mall: Massive centralised shopping centre.
*Orbital Logistics Systems: Massive AI servers, optimises factory output for the planet below.
*Orbital Filing System: Massive storage Servers for massed data output.
*Orbital Maintenance Drops: Packages delivered via orbital delivery, hoping this one gets installed.
*Noble Estate: High Quality Mansion type buildings.
*Orbital Psi Corps: School's for teaching psionically gifted individuals away from inhabited area's most likely to cause them distress.
*Orbital Shield Generators: Capable of erecting a massive defensive shield around a planet.
*Orbital Embassy Complexes: Self Explanatory.
Before we continue I must stress that everything you are about to read from this point forward is purely information made available to me through the local extra net, while I have personally step foot on the habitat and am reasonably certain of the possibility of the Orbital ring I fear I may be being fed false information going forward.
Science Nexus
A Megastructure which as a Salarian I appreciate from the bottom of my heart, a Mid sized Mega-structure designed specifically to facilitate R&D into a variety of different fields including engineering, physics, chemistry etc etc. Currently looking to see if any labs have a opening. Takes between 15 and 35 years to complete.
Sentry Array
A Megastructure I suspect the Turian Councillor can appreciate, a mid sized Array dedicated to information gathering, deep space probing and over all ensuring that there are no unpleasantness that is coming at a given sector, not only from criminals and asteroids but also full blown space borne monsters, I swear I'm not making this up. Takes between 10 and 25 years to complete.
Ringworld
Large Sized Mega Structure, this one being built around stars, preferably Blue Dwarf Stars but also equally possible to use on Yellow Suns as well. Can take as many as sixty years to complete to as few as twenty three depending on how many personnel one is willing to assign to it at the same time. Once work is completed four Habital segments, each capable of housing ten wards worth of space, will be locked into place around the sun in question and all habitability in the system will effectively be smothered to death.
Dyson Sphere
Large sized Mega Structure, again built around a sun preferably a Blue Dwarf, Can take between fifteen and fifty five years to build depending on the amount of personnel assigned to the project. The basic idea is a shell of solar panels built around a star that can be used to harvest all of the energy produced by the sun producing 4000 standard units of energy each year, equal to about one trillion times the energy produced by a standard council world in the same time span. I shouldn't have to translate this into Credits but the Lich Necropsy who has the largest number of Dyson Spheres? Easily the wealthiest faction within the Stellar Union. Even more important, completing a dyson sphere cuts off all sunlight in the sector leaving the system an uninhabitable series of tomb worlds. But they are not the only ones with gratuitous oversized space stations built around stellar bodies either. The Geth reportedly made plans to create a similar mega-structure for the purpose of housing their collective consciousness.
Matter Decompressor
Large sized Mega Structure, this one built in orbit around a black hole, takes between 15 and 45 years to build. Designed to use a Mass Effect field to pull material out of a black hole and then stretch it back into a normal state before shipping it away for use elsewhere. Although the idea is to harvest mineral material it is not the main material pulled out of the black hole, that particular honour goes to Eezo. I should use this as a opportunity to point out that most Union Technology doesn't actually utilise Mass Effect fields in the majority of it's technology, that isn't to say that it's absent either but if you have a better option than Eezo, or even excludes it then why would you? Eezo is needed for artificial gravity on most ships that don't rely on centrifugal force to maintain artificial gravity, but there's a big difference between keeping your boots anchored to the floor and covering the entire ship in a weight reducing Mass Effect Field. This same field can cause catastrophic damage from Exotic Plasma or Rare Crystal laser weapons, shields and propulsion. Because of this Eezo is largely treated as waste material, the Lithoids, the race predominantly responsible for mining black holes, tends to dump this material onto uninhabitable tomb worlds too far away from the sun to be of any real use and let the extra mass sink them into the Ideal Solar Orbit of Habitation, but are considered too toxic to be seriously considered for habitation. At least three of these worlds have been done like this already, The Asari Republic should make serious consideration to apply for colonisation rights to these worlds, with correct application of terraforming technology conditions can be very quickly made to become close to Thessia.
While I do believe that the Union may have more, or may claim to have more, near as I can tell these are the ones they're willing to go public with, for what reasons I'm not sure but perhaps as part of a false information campaign.