Some images I've collected of Shibam, a Yemenese city which, due to the unique vertical nature of its ancient buildings, is considered by many architecture enthusiasts to be one of the earliest examples of skyscraper construction.

The houses of Shibam are all made out of mud bricks, but about 500 of them are tower houses, which rise 5 to 9 stories high. This technique of building was implenented in order to protect residents from Bedouin attacks.