Merv was sacked by the Mongols.
Several cities existed on this site.
The site of Ancient Merv has been listed by the UNESCO as one of the World Heritage Sites.
... the United States Census Bureau, the town has a total area of 18.0 km² (7.0 mi²). 18.0 km² (7.0 mi²) of it is land and none of the area is covered ...