Storage tanks of olive oil. The high volume of masonry increases the thermal inertia of the tank: a constant temperature is necessary for good conservation.
<a href="//commons.wikimedia.org/wiki/User:Dvillafruela" class="mw-redirect" title="User:Dvillafruela">Daniel Villafruela</a>.
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>