The former One AT&T Center, now simply 909 Chestnut, will officially close on its offer this month. i've also gotten word that an architecture firm is moving into space on the 19th floor but I will not name them as nothing has been put out to press yet.
This would explain the increase in lights i've noticed on the interior over the last month or so. I do hope exterior renovations, including big lighting elements, get done as well.