In the center,at ground level, is a round pool of water.

VOA: special.2009.05.25

Later,we visit rooms below ground level.

VOA: special.2009.11.16

And the fields are commonly divided between level ground and a mountainside.

VOA: special.2010.04.13

WMO scientists assess and monitor air pollutants such as ground-level ozone,smog, particulate matter, sulfur dioxide and carbon monoxide.

VOA: standard.2009.03.23