http://www.pbs.org/wgbh/nova/lostempires/

Medieval Siege
In the Middle Ages, those who attacked castles used trebuchets, military engines capable of firing missiles with frightening force. In this section, view an actual trebuchet NOVA built, and construct and fire one of your own online. Also, find out what other weapons were used and what daily life was like in a medieval castle.

Pharaoh's Obelisk
The soaring stone monuments known as obelisks were the Egyptian pharaohs' way of capturing a ray of revered sunlight in stone. In this section, follow NOVA's ultimately successful attempts to raise an obelisk of its own. Also, learn where ancient Egypt's obelisks have ended up today, explore other Egyptian monuments using QuickTime VR, and more.