As a result of a visit to the Netherlands, I was informed about an excellent site which provides some photographic documentation of surface temperature sites in this country. Such metadata, of course, should be standard and readily available for all locations worldwide which are used in the construction of a global average surface temperature trend.
The site is (the information is in Dutch)
and includes the following observation sites
My only suggestion is that they need to also present views looking out in the cardinal directions from the site, as has been done by Anthony Watts and volunteers for http://www.surfacestations.org/.