How were catapults in medieval times built?

Depends of the type and situation. All of Europe had special mercenary units that specializes is seige warfare. That includes catapults. Some were built on the site by the mercenary unit hired by the army. Catapults were not easy to move around. read more

Some were built on the site by the mercenary unit hired by the army. Catapults were not easy to move around. To move most needed to be take apart and put back together on location. read more

Catapults made their exhibition in England in 1216 during the Siege of Dover, the French crossed the Channel and were the first to use Catapults on English soil. With war prevalent throughout Europe during the Middle Ages the popularity of fortified castle and city wall rose significantly. read more