Letters, We Get Letters!
As Dave Barry says, Alert Reader Susan passed on this valuable tip:

PENNSYLVANIA LINE:
A research Guide to Pennsylvania Genealogy and Local History
SW PA Gen. Services
PO Box 253
Laughlintown, PA 15655

On page 113 of the above publication is info about
Pennsylvania Panoramic Maps
Order these maps directly from the Library of Congress and request a Photographic Print Cost Quote
on any map as the first step in the ordering process.
Mail your request to:

Cost Quote,
Photoduplication Service,
Library of Congress,
Washington DC 20540 (2-3 wks reply)
or call 202-707-2677
and please mention The Pennsylvania Line as your source.

It then takes 4-6 wks for delivery after you order.
These are panoramic views to see what the town looked like from a birds eye view.

And the BEST NEWS OF ALL!!...
Landowners maps are also available for Allegheny Co
Map #701 for 1862
#702 for 1883
# 703 for 1890