Okay, I'm a guy. Even though nothing could convince me to fight a war anywhere, any time, I'm still fascinated by military stuff. I might even claim some small competence in military history.
So when in our travels we came across some operational siege engines, it was real cool.
This is a trebuchet in resting position:
The vertical beam is the catapault arm. There's a weight, barely visible, at the bottom. The two wheels to the right are used to raise the weight and lower the arm, preparing the trebuchet to shoot.
This is me, in dark top and blue jeans, plus five other guys turning the wheels. You see the weight is going up and the arm down. It's easy to turn at first, but becomes harder as the weight goes up.
The white ball at my feet is a plastic shot.
Now here is the trebuchet being fired. Keep in mind the size and weight when you see it flinging about. A shot could easily fly over a kilometer. As you might imagine, accuracy is not a strong point, but if your target is an entire city then it's kind of hard to miss.
Here's a ballista, a combination massive crossbow and catapault:
The crossbow part is the high, horizontal beam and ropes coming from it. The "bowstring" loops around the catapault arm, which you see resting at a vertical angle. You wind back the arm, then let go. The catapault is pulled forward, hits the "bow", and whatever's in the cup of the catapault goes flying.
Here's the ballista as seen from the receiving end. Imagine waking up to find a hundred of these parked outside your castle, all pointing in the general direction of you. That probably means it's going to be a bad day at the office. If men are assembling trebuchets being the ballistas, it's probably going to be a very bad day.
This is a battering ram. The roofing is to protect your people from arrows, boiling oil, etc, thus improving your army's occupational health and safety rating. The heavy beam under the roof is hung to swing backwards and forwards, making it easy to knock on the door.
These siege engines look exactly like the ones in Age Of Empires. Who says video games disconnect people from reality?