Castle

Castles were large fortified buildings, often used as the residence of royalty or nobility. On Earth, castles were usually located in Europe.

Castles on Earth
Castles located in Great Britain included Windsor Castle in England (TV: Silver Nemesis), Balmoral Castle in Scotland (TV: Tooth and Claw), and Cardiff Castle in Wales (TV: Everything Changes). A castle in Wessex was taken over by Irongron while the nobleman who owned it was away, but it was destroyed when Linx's spaceship exploded. (TV: The Time Warrior) A castle owned by Lord Geoffrey de Beauvain was taken over by Lord Waldean de Beauvain. (COMIC: The Magician) The Sheriff of Nottingham's castle was actually a spaceship that had assumed the likeness to disguise itself. (TV: Robot of Sherwood) Vicki lived near a castle when she was very young. (TV: The Chase)

Other Earth castles included Drachensberg (PROSE: Timewyrm: Exodus) and Colditz Castle (AUDIO: Colditz), both in Germany.

Some castles were converted into other uses. One became Stangmoor Prison (TV: The Mind of Evil), while another was used as the Pharos Institute's headquarters (TV: The Lost Boy). One castle in Scotland was used by the Quarks as their base, but it was destroyed by the Second Doctor and Jamie McCrimmon. (COMIC: Invasion of the Quarks)

When the Twelfth Doctor decided to meditate before his meeting with an old friend, he obtained a castle in medieval times (TV: The Doctor's Meditation) which he later threw a party in. (TV: The Magician's Apprentice)

Castles on other planets
The rulers on Peladon based themselves in the Citadel of Peladon on the side of Mount Megeshra. (TV: The Curse of Peladon, The Monster of Peladon) On Tara, Castle Gracht was the residence of Count Grendel of Gracht. (TV: The Androids of Tara) On the "vampire planet", the spacecraft Hydrax was converted into a castle by the Three Who Rule. (TV: State of Decay) Castle Extremis was used to host the signing of the peace treaty between the Anthium and the Zerugma. (PROSE: Martha in the Mirror) The residents of one unnamed planet, who were threatened by Mirrorlings, put all their mirrors in a castle to protect themselves. (COMIC: Mirror Image) Zentor lived in a castle on the Haunted Planet. (COMIC: The Haunted Planet) The sons of Grekk lived in a castle on an unnamed planet. (PROSE: The Sons of Grekk) A castle called the Space Citadel was defended by monsters. (GAME: The First Adventure) The monarch of Industry ruled from a castle. (AUDIO: Time Works) On Hedgewick's World of Wonders, there was a working castle known as Natty Longshoe's Comical Castle. (TV: Nightmare in Silver) A castle on Safeplace was actually one of the segments of the Key to Time. (AUDIO: The Judgement of Isskar)

Castles in other dimensions
The Gateway was a castle used by the Tharils as the centre of their empire. (TV: Warriors' Gate) Morgaine lived in a castle in her home dimension. (TV: Battlefield) The Pied Piper lived in a castle when he took the children of Hamelin to his own realm. (COMIC: Challenge of the Piper) The Sixth Doctor and Frobisher confronted Astrolabus in a castle in his realm. (COMIC: Once Upon a Time Lord) Eugene Tacitus' prison took the form of a medieval castle. (AUDIO: The Holy Terror)