 Silverstein Properties also has offices and the Silver Suites executive office suites in 7 World Trade Center , along with office space used by the architectural and engineering firms working on 1 World Trade Center , 150 Greenwich Street , 175 Greenwich Street , and 200 Greenwich Street . The building became fully leased in September 2011 when <unk> Inc. was reported to have leased a 125 @,@ 000 @-@ square @-@ foot space on the top floor . 
