This was a gigantic ship, 75 meter long, adaptable  to three uses (luxury passenger cruiser, merchant ship and warship). She was built circa 240 B.C. by order of the tyrant of Syracuse Hieron II, by the naval engineer Archias of Corinth under Archimedes’ supervision.
On the lower deck were the storeromms for supplies and commodities, a water tank, a fish farm, stables for horses, ovens, mills, labs, a pumping station, etc.
On the second deck were posh berths for the passengers and the officers of the crew, a kitchen, a gym, a leisure room, a library, steam baths, gardens, walkways, as well as a temple dedicated to Aphrodite.
On the third deck, the top one, there were peripheral walls with bastions and dozens of defensive machines, such as 8 towers, turtles, stone throwing cranes, iron hands, catapults, etc. On the perimeter of the ship, iron railings prevented the access of enemy vessels. She carried along a large barge, many boats and fishing boats.
For propulsion it relied on three sails and 20 rows of oars on each side. She only made a single voyage bringing grain from Syracuse to Alexandria, and she was donated to Ptolemy III Euergetes.
Only a decade later, Plolemy IV Philopator (221-205 B.C.) had a similar ship built (of a modern catamaran type) almost double the size (about 130 m) with  a double keel, the so called tessarakonteres (“forty-rowed”). The technology of Syracusia and the gigantic ships of the Ptolemies was lost and reappered in the Western civilization 1.500 years later.