ATTACK!!!!
There are a variety of official models of castles and fantasy from the Middle Ages, but I have a feeling that these MOCs you will love much more!!

 

Mechanized Orc Castle 03Mechanized Orc Castle 01Dwarven BallistasDwarfs Wars64042 War WagonDwarf Organ Gun - Front RightTWM Slasher R Troll War Machines SMB F 2 ESR Orc Ballista R Amaria's Siege Amaria's Siege Siege of the Royal Castle Siege of the Royal Castle Siege of the Royal Castle Pierian Giant Ballista The Fall of Cyrene Doorknocker1 Doorknocker5 CCCXIII - Lions at the Door When Themes Collide Trebuchet CCC_Negotiations Have Failed The siege of Eastgate The siege of Eastgate Trebuchet of Delos SiegeMain Trebuchet Troll Dreadbringer Troll Dreadbringer front Avalonian siege tower Palisade study Preparing to besiege 64019 Trebuchet Siege Tower Functions The Great Siege Age of Empires Collaboration Roman Ballista Roman Ballista Trebuchet Model Orc Catapult Orc Mantelet Trebuchet Simplified Orc Heavy Trebuchet Catapult - Nine Kingdoms (CCC14) Elephant Artillery 64018 Ballista 64041 Ballista Gathering of the Clouds War machine Hunter and Leonardicus testing new war machine Elephant rampage! (LCC) The Battle of Ainesford Trebuchet Ballista Scene Ballista Single