The Federation-class city ship is the largest type of ship used by the IGF. This gigantic type of cityship is used to house millions.
There are only about 20 of these ships active and in all of their history only 2 have ever been destroyed. These ships are scattered throughout the entirety of federation space.
They where created as intergalactic cruisers but when they where finished they where turned into the biggest cityship ever created by the IGF.
The ship is 20 km long, 7 km high and 8 km wide. They house billions of people and are used not only as ship but also as trade center, city and basically a planet.