Thornton Tomasetti amended its existing lease at 330 N. Wabash in Chicago, IL. The engineering firm expanded from its original 25,045 square feet to take over the entire 31,481 square feet of office space on the 15th floor of the landmark property. Thornton Tomasetti also extended its deal for five more years through the end of 2023. The lease makes the tower approximately 89 percent leased.