Castle
A castle was a fortified stronghold surrounding a keep. Humans and various alien species have been known to build them, often with incredibly similar designs.

History 
In 2372, Miles O'Brien and Julian Bashir visited the castle of the King of Leinster in a holosuite program of ancient Ireland. O'Brien insulted the King in his keep. ()

In 2374, O'Brien toasted the proposed retaking of Deep Space 9, calling it a castle. Bashir added "and planting our flag on its battlements, once again." Jadzia Dax thought they had been spending too much time in the holosuite. ()

That same year, in the holoprogram Leonardo da Vinci's workshop,  informed Kathryn Janeway that he had written to the King of France about his adventures in the New World. In the letter, he invited the king to soar with him from the towers of his castle. ()

In 2375, Elim Garak compared the Cardassian Rebellion's assault on Dominion Headquarters to storming a castle. ()

On the planet Megas-Tu, in an alternate universe, a castle was one of the many architectural items a sorcerer-contractor could build. ()

One of the stories in The Adventures of Flotter, a children's holodeck program, involved a giant beetle that lived in a castle. ()

While in the nexus, Jean-Luc Picard imagined his son Thomas Picard finding a toy castle in one of the s beneath the Christmas tree. Later he asked his father if he could help him build it. ()

The Hysperians, Humans who followed a medieval fantasy-themed lifestyle, lived in castles. ()

Castles 
 Blarney Castle (Blarney Stone)
 Castle O'Dell
 Glamis Castle
 Nottingham Castle
 Ogre of Fire's castle

Appendices

Background information 
Prior to the making of , an early story, titled Star Trek: Renaissance, which involved a Borg hive hidden in a castle basement was proposed.

External link 
 

de:Schloss (Bauwerk)
nl:Kasteel
Architecture