“In 1980, when I did the Palace Hotel on Madison Avenue, we produced the strongest concrete ever used in New York City. That was maybe 6,000 psi. Today we’re us

“In 1980, when I did the Palace Hotel on Madison Avenue, we produced the strongest concrete ever used in New York City. That was maybe 6,000 psi. Today we’re using concrete with 15,000 to 16,000 psi.” The twin towers, considered quite slim for their day, were 9.5 times as high as they were wide. Marcus’s firm is working on 111 West 57th St., which will be completed this year and has a ratio of 24:1