Stone Ship

Dwarven stone ships make use of Floating Granite to make very unusual floating citadels and ships. Most are the stuff of legend, as most of the time dwarves prefer to stay on land. They also tend to freak many people out as they are the size of at least a small mountain hovering above you.
It is likely the castle in Castledown was originally a dwarven stone ship eventually given elves and others. Other recent examples include the Sandstone Spire and the Shade Stone. Older variations include thy flying mountain of Dwarffenhold and the smoking barge of Greatforge also known as Dwanixo. Each of these has a size equal to a decent size town or a city. Also dwarves more often that others suffer from agoraphobia(open spaces) and acrophobia (heights) which makes the creation of these massive ships an anomoly and not common for dwarves.
Some smaller variations exist such as Kivan the Redbeard, with a stone platform and an almost nautical pirate ship that skims a few feet above the ground. Even though it doesn't need them, it sports the great sails of a three mast schooner. It's whereabouts over the last few decades is unknown.

Propulsion

Some just float and have no actual propulsion, others use great holy shrines or magical forges to propel the ships.

Armor and defense

Being massive stone, they tend just to be hard to puch through and are often immune from all but the most powerful magics from below. From above the structures built on top are succeptable to more damage from conventional means.

Hangars & docked vessels

Most don't drop to land on the ground so have a mix of smaller vessals, winches and platforms for loading/unloading cargo as well as passengers.

Rarity

Rare to Very Rare, all are unique

Speed

Usually 5-30 miles per hour, rarely they can go faster.