Here’s a sneak preview of the Martian Battleship concept art, which comes courtesy of our friend SickJoe. There’s both a version with the weapons deployed and one with them stowed to minimize its radar cross-section. The mess of machinery at the rear is a heat-sink system designed for physically ejecting waste heat from the ship when it builds up, and you can see the two super-railgun turrets too.
If you’d like to check out more of SickJoe’s art, you can find him over here: https://www.deviantart.com/sickjoe