Even if you aren’t running, the Pittsburgh Marathon is going to be part of your Sunday. The outbound route goes along one border of Polish Hill, on Liberty Avenue, and returning, it will go along Penn Avenue. Streets along the route will be blocked off, bus service will be detoured, and in general it seems like it might be a good idea to just stay in the neighborhood until later in the afternoon.
Here are links for information:
Marathon route map.
Bus detour information. The 54 route is on this list.
