Then as now, water is central to life in Jordan. This cistern, called a Birka, was built around 730 AD to serve the needs of the Umayyad city that existed that that time. It is about 58 feet in diameter roughly the same depth. Built with 8-foot thick stone walls covered in waterproof plaster, this cistern was built to last -- and it has. It was designed and placed to collect and save water that ran off from the roofs of neighboring buildings -- a water conversation technique that is being "rediscovered" today in the USA and Europe.