Cliff dwellings have historically offered attributes that lowland abodes can't match. As far back as A.D. 600, the Anasazi people, who once lived in what is now the American Southwest, built precipitously high in the sandstone cliffs -- likely for protection from enemies. In medieval times, as barbarian hordes wreaked havoc across Europe, monastery towns perched high up on the Amalfi Coast afforded excellent vantage points from which to observe the gathering militias. (Today the cliffs are more likely to attract armies of jet-setting moguls.) In peaceful times, a clear view from high atop a cliff was deemed spiritual, bringing pilgrims closer to God.