These two blocks formed the thesauros – a collection box for monetary offerings. They were discovered in 1988 on the north slope of the Acropolis built into a 19th-century house which was demolished. Most likely before they ended up there, they had been incorporated into the Rizokastro, the medieval wall surrounding the Acropolis, on top of which the house was erected. This site is located a little lower than the Sanctuary of Aphrodite Ourania on the slope where the collection box initially stood.

The two blocks fit together, one above the other. On the box’s upper surface there is a slot where people would drop their coins into the hollow carved in the lower stone. On the front and back sides indentations were used to secure locking mechanisms and on the lateral sides traces of two ridges mark the place where a rope was fastened to raise the upper block when the money that had been collected was needed to be counted.

The device’s purpose is revealed by an inscription on the front which reads "treasure of pre-nuptial offerings to Aphrodite Ourania". Below the inscription the carved symbol of a silver drachm indicates the sum that needed to be deposited so that the goddess would ensure a happy married life to the new couple.