Mies's updated plans were filed with the DOB in March 1955; the updated structure was slated to cost $20 million (equivalent to $ million in ). Mies's plans were listed in DOB records as a modification to Pereira & Luckman's original plans, rather than a completely new building plan. At the time, twenty of 250 existing tenants on the site had already left. Cushman and Wakefield were hired as rental agents. The proposed tower was described in "The New York Times" as one of several on Park Avenue that "add up in sum to a boom". By mid-1955, the architects had specified the tower would be made in bronze and glass. Demolition of existing buildings on the site began in late 1955 and was completed in March 1956.