This trebuchet, along with two other siege engines on show at the site, is a modern reconstruction based on medieval drawings. The trebuchet was part of a range of formidable machines used to attack the walls of fortified sites during sieges. It is a sort of giant catapult, capable of launching projectiles using a lever with a counterweight at the end. Campaign catapults were pulled on travelling carriages; fixed catapults would have been built at the actual site of the siege.
The trebuchet at the Château des Baux measures 16 metres in height. As powerful as it is accurate, its lever arm system would have allowed boulders weighing 50 to 100 kg to be fired over a range of 200 metres. As it weighs 7 tonnes, 60 soldiers would have been required to install and operate it. This trebuchet is a unique model which has a quarry-wheel arming system, in place of the usual winch system.