The completed Singer Building was composed of a 14-story base covering the entire lot, and a tower rising an additional 27 stories above a small section of the base. Included in the base were the original Singer Building at 149 Broadway, the Bourne Building on Liberty Street, and subsequent additions to both buildings. The facade was made of brick, stone, and terracotta, and a dome with a lantern capped the tower. The foundation of the tower was excavated to the underlying bedrock, while the base rested on relatively shallow foundations. The Singer Building used a steel skeleton, though load-bearing walls initially supported the original structure prior to modification. When completed, the building had a large lobby, 16 elevators, and an observatory.