CHICAGO—With so much new office space having opened up in and around the CBD over the past year, and with new projects underway, it’s a good time to take a look back on the most significant deals of 2017. It wasn’t the most lucrative office deal of the year, but when Northern Trust agreed to occupy 468,000 square feet at 333 S. Wabash. The distinctive red tower in the East Loop, formerly known as the CNA Tower, looked like it would empty out when CNA decided to drastically reduce the amount of downtown space it occupies by relocating from 750,000 square feet to 272,569 square feet at John Buck’s 151 N. Franklin, a new trophy building which the developer plans to open in June. But Northern Trust showed that such shadow space, even in a 1970s-era building like 333 S. Wabash, is still quite desirable. If it can still get filled, that bodes well for the several mammoth new projects, such as the Old Main Post Office redevelopment, already underway.