There are numerous empty/parking/underutilized (e.g., one-two story) lots in and around 30th Street Station that could be developed. Not to mention that whole "Innovation Neighborhood" on JFK Blvd between 30th and 32nd. The area between the River and say, 34th Street has ample room to grow, Penn Park notwithstanding. This is probably the most offensive lot -
https://goo.gl/maps/wsNjf. I'm not too concerned with that union building, as ugly as it may be.