Here is course information for the 2012 Pittsburgh Marathon, which kicks off Sunday morning at 7:30. The half marathon and marathon relay will also begin at 7:30, and all three races will start at Liberty Avenue between Sixth Street and Seventh Street.
Here (PDF) is a map of the marathon course. Runners start downtown (here is a PDF map of the starting line area) and will then make their way through the Strip District. After that, it's on to the North Side, then the West End and the South Side. Then the race will head into Oakland and Shadyside, then on to Point Breeze, before reaching its easternmost point at Homewood. After that, runners will head through East Liberty and Highland Park, then head southwest to Friendship and then Bloomfield. The race then heads back downtown. You can find course directions here (PDF). Here (PDF) is a map of the finish line area.
Follow SB Nation Pittsburgh throughout the day for updates on the results of the race.