Apart from the cannon in the foreground they used (again from the Wikipedia:) a trebuchet or trebucket [which you see painted in the background]: is a siege engine that was employed in the Middle Ages either to smash masonry walls or to throw projectiles over them. It is sometimes called a “counterweight trebuchet” or "counterpoise trebuchet" in order to distinguish it from an earlier weapon that has come to be called the “traction trebuchet”, the original version with pulling men instead of a counterweight.
The counterweight trebuchet appeared in both Christian and Muslim lands around the Mediterranean in the twelfth century. It could fling three-hundred-pound (140 kg) projectiles at high speeds into enemy fortifications. On occasion, disease-infected corpses were flung into cities in an attempt to infect the people under siege—a medieval variant of biological warfare. Trebuchets appear in China in about the 4th century BCE and in Europe in the 6th century CE, and did not become obsolete until the 16th century, well after the introduction of gunpowder. Trebuchets were far more accurate than other medieval catapults.