A battleship armed with eight Schwerer Gustav guns

How large would a ship need to be to carry four twin Schwerer Gustav gun turrets?

Probably around 150,000 tons or more, with the loading system and very slow rate of fire making the concept impractical.

The enormous barrels, shells, loading equipment, and structural support push the estimate toward roughly 150,000 tons before allowing for German specialization and overengineering. A firing cycle measured in tens of minutes would make the ship tactically awkward despite its spectacular caliber.