One of over 50 round towers (or rather, their ruins) dotted all over Sifnos, mostly on ridges or coastal points. This one is inland, on the way to Vathi. Archeologists aren't sure of their purpose (one theory is that they were beacon stations, places to light fires that could be seen from the next station, as warnings of attack) but they date from the height of the ancient Greek empire, around 500BC. Most of them have been largely destroyed but their circular foundations can be discerned on hilltops (not to be confused with not-quite-as-ancient aloni ) or mingled with more recent stone buildings. (Want a closer look?)