The cistern of the Holy Anargyroi was designed and begun in the Napoleonic period. Work stopped for several years, resumed in 1818 under British rule and finished in 1821; a local newspaper records a rebuilding in 1861.

It was the first large public cistern on Paxos, and on its own it held enough water for Gaios.

The tank is cylindrical, with a low circular enclosure and a handsome central mouth that carries the date of construction. The inscription sits on the axis of the raised paved catchment that runs from the gate of the enclosure to the mouth, so that the whole surface is a funnel. The gate is reached by a short flight of steps, and the approach is paved in a delicate pattern of long slabs set among smaller stones. The workmanship is the clearest surviving evidence of what British public works on the island looked like, and of how good the local masons were.

Parts of the structure are visibly coarser, with simpler paving: these are probably the additions of 1861, after the British had gone.

On an island with almost no springs, cisterns were not infrastructure but survival. Paxos has dozens of them, and this is one of the two great public ones in Gaios.

The rainwater was poured in through six square intake spouts set at the points of a hexagon, now covered with thick stone slabs, and the paving of the circular surface is laid out geometrically around them. The two long side surfaces attached to the enclosure were added later: their coarser work suggests the repair of 1861, a last effort to collect more water a few years before the British left. Each is tilted towards a shallow half-pipe channel that feeds the two spouts on the central enclosure.

The cistern is a listed monument of the Ministry of Culture.