Tower Maps
AGL "Above Ground Level"
This is typically the height of the tower above ground, measured in feet. The height is the approximate height at which antenna space is available. The AGL for buildings it is typically the height from street level to rooftop.
The AGL is used in conjunction with Ground Elevation and AMSL data.
Calculating HAAT
HAAT is defined as "antenna height above average terrain"
See the FCC's online calculator.