The World Heritage List and official web site (whc.unesco.org) is maintained by the World Heritage Centre, a part of the United Nations Educational Scientific and Cultural Oranization (UNESCO).
Coordinates on the World Heritage web site -- unless we are informed otherwise -- are taken from official information provided by the national authorities in the country where the site is located.
Some of this information is very old -- and very little of it conforms to the current standard of WGS84. Sometimes this is obvious, and we make adjustments to correct the errors; more often than not, however, our accuracy is limited by the resolution of the map software (or the Google Earth image).
Google Earth has now made it much easier to verify coordinates -- but we cannot do it all at once! Nor do we have a person dedicated to checking all 812 locations. Readers of this post who spot errors in coordinates provided by the web site are urged to write us with this information and we will endeavor to correct these problems as soon as possible.