The roofs of the buildings were slanting, with wooden or galvanized iron walls.  Some of the more important of them, such as stores, warehouses, government buildings, etc., were quite large, and stood upon piles to keep them out of the way of floods which often sweep the lowlands in the rainy season.  In many of the streets ran canals, which their small guide told them, in pidgeon-English, were drains for the floods.  And he also said that the long embankments which the boys saw stretching along the sea front were dykes built at great expense by the sugar planters to keep these same floods from washing the rich soil of their fields out into the ocean.