Work on the Municipal Building officially started on July 17, 1909. One observer predicted that the building's construction would result in an increase in real-estate values, similar to what the Flatiron Building had done for the Flatiron District. Foundation work was completed in October 1909, and revised building plans were approved by the Board of Estimate that November. Bids for the construction of the superstructure were opened on December 21, but an injunction against the awarding of the contract was placed less than an hour after the bidding process started, after a lawsuit was filed over the fireproofing material that was supposed to be used in the building. Furthermore, the presence of the sand posed issues for the superstructure, though McClellan said that he believed it was safe to build on sand. The building's cornerstone was laid a week later, and the injunction was reversed. Unlike at other projects, the groundbreaking ceremony was private, and the cornerstone only had the year "1907" inscribed in Roman numerals.