Above and below downtown Pittsburgh, a network of pedestrian passages offer shelter from the weather and traffic. Most of these routes are easily accessed and open to the public. And with a little planning one may pick up a bite to eat, run some errands, do some shopping, take care of county business and more with only a minimal exposure to the outside world. Although the building owners and security personnel may not approve, this system of sheltered pedestrian passages may be expanded to include building lobbies.
Many buildings have entrances on more than one street.
Another network is to be found in Oakland, connecting many of the hospitals and the University of Pittsburgh campus.