In an article about the Chambers Street Station in the New York Division of the Electric Railroaders Association by David E. Rogoff ( Vol. 2, No. 3, July-August 1959, p. 5 ), Rogoff wrote that work on the Municipal Building began on January 27, 1907. Soon construction crews ran into problems with the soil. The site of the future Municipal Building was the site of a "Little Collect Pond" that was 60 feet deep and surrounded by a 100 foot hill. This hill was leveled off between 1803 and 1811 but the bed of the pond remained and caused construction problems. South of the site was a swamp and in order to construct a large office building, piers had to be sunk 130 feet below the street surface. Let us see how a map shows the typology of the area from surveys taken during early New York. These features are shown on a map with a street grid of the late 19th Century. A great resource is the University of Texas map room at Austin that has a great deal of "cool stuff ", on history and transportation from all over the world. This map was taken from their cool website.
The area is relatively flat except towards the south as you go towards the Brooklyn Bridge and the East River.