Six Famous Walls

Sometimes it's hard to come up something to write about. But when you stare at the wall to think of a subject, it seems natural to write about walls. Here are six of the most notable.
Jericho
The Walls of Jericho were made famous by tumbling down. The city of Jericho, on the West Bank near the Jordan River, has been occupied in one form or another since 9,000 BC. The Book of Joshua in the Bible describes the Battle of Jericho, where the Hebrews circled the town seven times and the defensive walls of the city collapsed. It was the Israelites' first victory in the conquest of Canaan. Archaeology at the site shows the city has been destroyed and rebuilt many times.
More walls, after the jump.
What other walls belong in the "famous" category?