[4] Penn Mutual's original Philadelphia headquarters was erected in 1850–51 to designs by architect Gordon Parker Cummings, at the northeast corner of Third and Dock.

[7] In February 1889 the company moved out, temporarily, so that property could be cleared to prepare for a new edifice "to be as high as the Record cupola", the conspicuously tall Philadelphia Record tower standing immediately adjacent on Chestnut.

In 1916 Penn Mutual moved to an entirely new headquarters designed by Edgar Viguers Seeler, at the corner of Walnut and 6th Street.

Their Penn Mutual Tower project encompassed a third, higher modernist glass tower, the preservation and integration of the 1916 structure and the 1931 structure, and a move further east along Walnut which incorporated another unrelated historic property—but only as a facade, a freestanding scrim.

[10] That building had its own history as the Pennsylvania Fire Insurance Company Building, 508–10 Walnut Street, designed by John Haviland in 1838 originally with four stories, three bays, and the winged suns and papyrus-leaf-column decorations of Egyptian Revival.