Construction had reached the 26th floor by the end of April 1962. Upon completion of the floor, work was to begin on the tower's bubble dome. By June 1962, ABCC loaned an additional $300,000 to Caroll, who reached his $3 million loan limit with the company. Caroll ultimately owed ABCC a total of $3.5 million. In August 1962, the Landmark tower was designated as a civilian fallout shelter, with the capacity to hold 3,500 people after its completion. That month, work was underway on the steel framework base for the tower's glass bubble dome.