Fortifications unearthed in Jericho dating back to 6800 B.C. confirm that it is the earliest known walled city, and evidence of other habitation in the area dates back about 11,000 years, which means it is a serious contender to be the world's oldest city. Incredibly, Jericho has remained inhabited — and dry — throughout history, despite its location well below sea level. This fact also makes the city the lowest permanently inhabited site on Earth. Today 20,000 people call Jericho home.