The Mensa Ponderaria was Pompeii’s public system for checking the capacity measures used in trade. It occupies a niche cut into the western perimeter wall of the Sanctuary of Apollo, beside the Forum.
The counter has several cavities of different sizes into which liquid or solid goods, such as grain, could be poured to verify their quantity. The city authorities thus had official reference measures with which to check that commercial transactions were conducted correctly.
The structure already existed in the pre-Roman period, as three early inscriptions in the Oscan language attest. After the Roman colony was founded in 80 BC, these inscriptions were erased and the measures were adapted to the Roman system. A Latin inscription records the intervention of the civic magistrates responsible for standardisation.
The Mensa Ponderaria visible in Pompeii today is a copy; the original is held in the National Archaeological Museum of Naples. The monument was brought to light during excavations in 1816–1817.
