The T station at Gateway Center Station, rebuilt in 2012.
The Port Authority of Allegheny County's Light Rail Service runs 26.2-miles from the North Shore and Downtown Pittsburgh through Pittsburgh's southern neighborhoods and many South Hills suburbs. The Port Authority seems to change what it calls the service on its schedules periodically: for a while it was the blue and red lines, then the subway line. You'll need to know that if you're perusing the official trip planner, but everyone calls it the T.
Fare is free the same as the bus: Zone 1 (fairly close to the city) costs $2.50 to ride. Fares increase with distance from city. T Lines MapFare Information