The Ark is the main 'building' of your little fleet. It contains some of the most important things like the bridge and the barracks. The Ark can relocate by using slowly auto-regen fuel to move slowly or use gold to teleport.
The Ark is extremely reminiscent of a world war 2 battle ship, despite having no main batteries, it does however have a singularity rail gun that makes it look a little like Space Battleship Yamato.
The ark is Brown in color and appears to be slightly cobbled together.
The ark houses your garrison, bridge, barracks and much much more. Though it cannot be destroyed resources can be taken.