There are several ways for you to find the atlases you are looking for. The atlases are arranged by location, year and types.
If you know the exact (or approximate) location you are looking for, click on the county. The Philadelphia county is further subdivided into the different wards.
All of these atlases are arranged in chronological order, with links to an extended display of each entry.
There are atlases of six railroad lines that cover the five counties.
Fire insurance atlases are arranged by the publishers: Hexamer, Ernest, and Son, Sanborn Map Company, and other publishers.
You can find here the Genealogy of Philadelphia County Subdivisions.