Downtown Athens at 20.2°C average annual temperature

Actually there are two in the hill of Nymphs (plus one more in the Pnyka hill).

The first one is purely to cross check the values of the A class Stevenson Screen

You can find its online values here

www.iersd.noa.gr/WeatherOnLine/s_Thiseio/meteo_tableGR.html

The first pic is of that second one

The actual A class Stevenson Screen is off view (I mean you can't catch it on google earth easily). It's completely fenced with various yellow plated markings either on the ground  or next to the SS itself indicating height (in meters and cm) from ground, distance from nearest blockages (trees, buildings etc) from all directions according to WMO guidelines. It's very very pedantic but they have their reasons. 

Back when the bailout crisis emerged in Greece the National Observatory of Athens was ''attacked'' by the Troika for overspending and not sustainable research staff. It was huge news internally in Greece and the then government did not back down. Instead they doubled down and passed extra protections for the organization. Among these the circular order published at the government gazette noting that the historic SS station can not move locations among other things on the public status of NOA. NOA narrowly escaped Greece's financial melt down. Instead they came out winning big since this publicity attracted private sector interest with the Onassis and Niarhos Foundations funding the 600+ Davis fan aspirated stations all over the country. 

Remember NOA plays a central role in modern Greece's politics. It has been in the forefront of various political crises linked with Greece. Even during the German occupation of Greece the SS station did not stop operating and the NOA itself was respected by the Nazi's. Generally is one of Greece's symbols of resistance through time. It's a pity the morons in the far right often weaponise it.  

Anyway I remember a few years back that I could get a glimpse of some of these yellow marking/signs through google earth just at the edges but not of the actual SS itself. But if you stroll around the Thiseio area for a coffee there are some hidden spots from where u can get a glimpse of the actual A class SS station. But u will need binoculars