The first large ships the Asgardians designed, based off inspirations from earth as well as from a die-cast model found in a workshop in Central Commands secondary habitat modul.


Drive system: Orion - nuclear pulse drive
http://en.wikipedia.org/wiki/Projec....._propulsion%29

Overall overview / reference:
https://en.wikipedia.org/wiki/File:.....figuration.png



Three ships were build so far by 2012:
Argentine ( Freighter )
Brasil ( personnel carrier / luxury liner )
Chile ( long range explorer )

The City Class:
The name "City-Class" was given AFTER the names had been selected.
Originally the name of the class had been "Country-Class" as it was intended to use those ships to welcome potential visitors from earth.
However , after it got clear that there wouldn't be any spaceships from Earth anytime soon as earth plunged from one conflict into the next instead of starting space exploration and actually solving most of the issues on earth by tapping the unlimited ressources of the solar system, the class was relegated to "City-Class" as plans for larger ships with better drive systems were found.
Yet, as long as the underlying drive systems are not fully understood ( Daedalus drive; http://en.wikipedia.org/wiki/Project_Daedalus , magnetically channelled fusion pulse drive ), there won't be any such ships built, as it's considered suffiicent to keep the three city-class "megaliners" in operation and upgrade them once the Daedalus drive system becomes available.
All City class vessels carry a 10 foot ( on average - some parts have less, others thicker armor ) Pykrete armor ( http://en.wikipedia.org/wiki/Pykrete ) under their outer soft iron shell, which protects against stellar radiation, heavy impacts as well as buffering large amounts of water and organic matter.


The Argentine:
As a lot of the small stations in the Asteroid belts were found damaged, moving in of sufficient material to repair and rebuild them became neccessary. As the robotic drones need a working infrastructure, the Argentine was build without a personnel compartment, but only the forward hydroponics and crew section, and instead a giant cargo space, which allows it to haul both a fully automated factory modul plus servo robots along as well as carrying special raw materials , like fertile soil, seeds and others substances along to repair a station and man it before leaving for refitting, loaded with ores and defective machinery for analysis and repairs.


The Brasil
Most of the small stations are running fully automatical, and even the important spacestation Odin is seriously understaffed, which the canine council on Asgard considers a risky thing in many ways, incest just being one of them.
Accordingly a fast way to move large amounts of personnel was needed, and the Argentine showed the new vessels were easily able to do the job.
Accordingly the second model built received a rotating habitation module instead of a cargo module, with all the luxury possible.
The fact the Brasil is faster than the ferries on long distances makes travels to the outpost at Tau Ceti's Nadir a pleasant ride which is often also used by married couples to see the giant installation that serves as the one way link to earth. Where Ferries need almost a year to reach Odin, and crews are accordingly selected with social reliability as a main factor, the Brasil needs only 6 months, and its spacious installations give the feel of a small habitat instead of a ship, so it finally permits transferring also not that robust personnel to the Odin station.

The Chile
Third ship of its kind, the Chile is a mix between the Argentine and the Brazil.
Equipped with a personnel habitation module in the cargo hold, but the dedicated crew module removed and replaced with workshops and extended storages, it sports vastly extended hydroponics and also posesses an area for lifestock to be carried along.
Designed for a crew twice the size of the Argentines complement, the quarters are spacious and it's luxury exceeds that of the Brazil.
The cause for this extreme modification is however pure neccessity.
Designed to carry a crew of all sapient species of the Tau Ceti system, a mixed, self sustaining food supply was just as neccessary as sufficient space to prevent social tensions.
Additionally the workshops and material storages and the large food supply base is neccessary as the Chile is scheduled to travel far beyond where the Odin space station serves the two telescope-arrays Hugin and Mugin, as far as to the Oort' cloud of the Tau Ceti system. If there is trouble, the Chile will be totally on it's own, as only the Argentine might be able come to help, and even that might take a year at the barest minimum.
Notes and construction designs found in Asgards Databases show that there should be further installations at the outmost rim of the system, and travel to there takes even the swift City class vessel not only "a few months" but years, considering a fuel efficient mode of travel.
And that is neccessary as a large area will have to be searched systematically.

As of today the Crew for the Chile is still undergoing training, science, research, navigation, engineering, medical and, too, military forces, have to be trained to work together, to handle the latest equipment and the complex systems of the huge vessel. And everybody has to be a specialist in at least two fields, as accidents, sickness and death can happen every moment in space.
Even childcare is considered mandatory on a cruise thats going to last at least 5 years, so nursing, childcare and teaching are just as neccessary skills.