New York City architect William L. Bottomley and his partners designed the former custom house in a streamlined Spanish style, architecturally evoking Texas's eighteenth-century Spanish identity but with a dash of modernistic asperity redolent of the 1930s. The three-story, symmetrically composed, tile-roofed building is raised a full story above grade on a landscaped city block dotted with palm trees. This elevation of the ground floor, more characteristic of residential architecture than of institutional, indicates Galveston's extreme vulnerability to the flooding associated with tropical hurricanes.