Wales must have more castles per square mile than any other place in Europe. However, the lion's share were not built by the Welsh, but by English invaders. In the fortified castle town of Conwy, we learn from a local expert how these castles were carefully engineered to discourage and withstand Welsh rebellions. For more information on the Rick Steves' Europe TV series — including episode descriptions, scripts, participating stations, travel information on destinations and more — visit www.ricksteves.com.