Typical colonial houses in the Historic Center DistrictParaty. Once a month when there is a Full Moon and the tide is high, seawater rises from its normal levels, and pours into the Historic Center District through special openings in the seawalls that separate the city from the harbor. The streets are only flooded for a short time, until the tide recedes. The water is usually only six to ten inches deep and a few merchants near the seawall put out small bridges to span the flooded streets for the benefit of pedestrians..