White Construction of New York built Fire Control Tower No. 23 using a sliding form, or slip form, method that allowed a continuous pour of concrete. In June 1942, about fourteen piles were driven into the ground, and two wooden cylindrical forms of tongue-and-groove board were placed one inside the other with a one foot gap between them. Iron reinforcement bars were positioned in the gap and concrete was poured; as the concrete set, the forms were jacked up and the pour continued. Rectangular boxes placed in the gap created window openings. A line near the top of the tower marks where the pour ended and more traditional forms were used to create the top and cap. The shell of Fire Control Tower No. 23 was built in only 2 1/2 to 3 days, and finishers then created the floors and details before the tower was completed by September 1942.