Like ghosts from the past, sunken villages at the bottom of water reservoirs are not meant to be seen. But the ruins of Kallio in the mountains of central Greece are becoming very much visible - and they have a warning to deliver.
As an unprecedented drought induced by climate change rampages across much of southern Europe this summer, reserves at the artificial Lake Mornos - the biggest of the four reservoirs supplying drinking water to Greece's capital, Athens - have hit their lowest in 16 years.
The receding waters have exposed what was left of Kallio, a village submerged in the late 1970s to create the reservoir some 200 kilometers (125 miles) from Athens.
Colonies of freshwater mussels sprout from cracks in the muddy stonework - the now-empty shells tinkling like wind chimes in the breeze, blending with the sound of cowbells from herds grazing around the lake.
Greek authorities insist there is no cause for alarm, yet.
