Take one of the inclines (aka funicular) up to the top of the hills surrounding the city. Great views and $3.50 roundtrip beats hiking up here. I took it up at night so the city and bridges were lit up with a crystal clear sky. Beautiful.
You buy your ticket at the machine in the lobby of the station. You need to get a zone one with transfer in order to make a round trip. I'm thinking these might be the same tickets once would use on a bus but I'm not 100% sure. Currently the cost is $3.50.
The ride itself takes about 2 minutes. These cars are small so I can see there being a line during rush hour or peak tourist times. It's part of Pittsburgh history. Ride it at least once.