One Liberty Observation Deck
Sure, the Comcast Center is taller, but unless you're buddies with Brian Roberts, you're probably not getting up there. Instead, for $19 (kids are $14) you can get a 360-degree look at the city from the 57th floor of One Liberty Place. Make it an after-dinner activity (it's open till 10 p.m.) to see the city twinkling at night.
1650 Market Street, Philadelphia, PA | 215-561-3325 | Website