A couple of issues regarding the coordinates for THESSALONIKI.
a. 456-001 City Walls
. These are given on the UNESCO web site as "N40 38 20.30 E22 58 13.10" (40.63897, 22.97031). This is clearly incorrect as, when transferred to Google maps it lands well outside the Walls in the middle of Highway 25.
I don't know if that was the reason that the Thessaloniki landmark of the White Tower was chosen to represent the City Walls on our map - which it does at the present. I note that several reviewers refer to the White Tower but I do not believe that it is actually a part of the inscribed "walls". The UNESCO map located here - http://whc.unesco.org/document/105005
provides the coordinates of 516 locations which trace the walls around Thessaloniki!! The last of these, which locates the inscribed Eastern end point of a small stretch of wall in Filikis Etarias St, does NOT reach the White Tower but is situated a couple of blocks further north at 40.62791, 22.94976 . I note that the UNESCO Gallery of photos includes the White Tower - but then it includes one of the Arch of Galerus also and that too is NOT a part of the inscribed site! UNESCO has "form" in other WHS in providing photos of locations not actually included in the inscribed areas so that need not really bother us as "evidence"! Wiki points out that the current tower was actually built AFTER the capture of Thessaloniki by the Ottomans - albeit on earlier foundations (though this date is not fully accepted and some sources date it to the Venetian period immediately before the Ottoman Capture). It is also significant that the Wiki article on the Tower makes no reference to it being a WHS - whereas other inscribed elements such as Vlatades Monastery and Agios Dimitrios Chruch are clearly given their WHS status.
My final "evidence" consists of the map I obtained titled "Thessaloniki UNESCO Monuments"
given out by the Tourist office in Thessaloniki. This shows the locations of 15 monuments, coinciding exactly with the number of inscribed elements as listed by UNESCO. The White Tower is, however, NOT given a number - in fact the location chosen for No 1 City Walls is a relatively minor one at the Western end. The same is true of a section in the rather nice 110 page handbook on the City which they also hand out. This includes a section "1st Walk - UNESCO Byzantine Monuments"
which again contains 15 elements and again fails to utilise the White Tower to represent the Walls - instead 4 different locations along the northern perimeter are used.
Which leaves us with the question - if the White Tower is not relevant which coordinates do we choose for this inscribed element??
I propose that we adopt a location along the North Eastern section at the "Kastro"/Acropolis- 40.644520, 22.961608
b. 456-007 Church of Panagia Chalkeon
The UNESCO coordinates for this are given as N40 38 40.00 E22 57 27.60 . But these are wrong and would actually be suitable for the Walls!! However the location chosen for our map on Olimpou St is ALSO incorrect as can be seen by looking at the map and going SSW for about 4 blocks where the actual location will be encountered at 40.636803, 22.943651