Much of the interior and exterior design of the Philadelphia temple was influenced by other historical American Revolutionary era buildings.
On the exterior, the two towers were inspired at least in part by Christ Church in Philadelphia and Independence Hall. However, instead of following the traditional one tower design of early Colonial churches, the temple uses two towers, to point back to the early LDS temples of Salt Lake, Manti and Logan. The top oval shape windows also hearken back to similar shaped windows of the Salt Lake Temple.
|Broken pediment above recommend desk (left) and original millwork in Independence Hall (right)|
Light Fixtures and Vases
The Philadelphia temple includes various examples of elegant historic light fixtures and vases. The baptistry incorporates a beautiful huge brass fixture above the font, with similarly designed brass fixtures throughout the temple. The chandeliers in the second instruction room, were designed to replicate the "crystal fixture hanging in the Assembly Room of Independence Hall."  There is also an enormous breath taking crystal chandelier in the Celestial room. Several examples of beautiful lamps and vases with traditional designs can also be seen, including some with scenes of early American harbors.
|Light fixture in second instruction room (left) with original fixture from Independence Hall (right)|
The flooring throughout the temple was designed to replicate the floors of early American buildings, with wood floors, rugs, and tile, instead of the more modern wall to wall carpets. The first floor uses checkered dark and light shaded stone tiles, reminiscent of colonial buildings, while the upper floors use solid wood flooring overlaid with beautifully crafted rugs. The Celestial room, with its elegant wooden floor and embossed rug, is uncommon among LDS temples, as almost all other Celestial rooms are covered with only carpet, creating a truly unique experience.
Paintings and Murals
Many of the paintings and murals of the temple were chosen to highlight several important historical events that took place in Pennsylvania. One very unique painting for an LDS temple is found in the lobby and depicts the signing of the Constitution of the United States. The mural in the baptisty depicts the baptism of Joseph Smith by Oliver Cowdery, which took place in Pennsylvania in the Susquehanna river in 1829.
|Beautiful mural in the first Instruction room of the Philadelphia temple|
Patterns and Motifs
Perhaps one of the most significant motifs in the temple is the double quill pen motif. This design comes from the original quill and ink well used for the signing of the Declaration of Independence found in Independence Hall. A two quill pen motif is also found in the woodwork of the table in the Celestial room.
|Double quill pen motif (left) and original ink well used for signing of the Declaration of Independence (right)|
The mountain laurel, the state flower of Pennsylvania, is also found within the temple, in particular in the bronze metal work of the main exterior doors, in the railing around the baptistry, and in the stylized cast plaster work of the Celestial room.  A beautiful lily flower motif is also found in this same cast plaster at the top of the Corinthian capitals. The three petal lily in early Christianity often represented the Godhead, and at times was also associated with the three virtues: faith, hope, and charity. 
|Eight sided star motif (including the seal of Melchizedek)|
Temples are designed to symbolically show how one moves from a worldly existence, to that of heaven. Elements of architectural design were used to help show this progression within the temple.
|Three styles of columns in the Philadelphia temple (Doric, Ionic, and Corinthian)|
The exterior stonework also point to this symbolic progression within the temple. The first floor is marked by a large strong base-like foundation where the administration rooms, and the baptistry is located. This base symbolically reflects how baptism is the foundational ordinance of the gospel, and how the other ordinances are lifted up on this foundation. As you climb the stairs of the building, you come to the second floor changing rooms, then up to the third floor with its more significant rooms where the higher ordinance of the endowment occurs. Finally, as you come to the fourth floor, you enter the sealing rooms where the culminating ordinance of the sealing of families takes place. The placement of columns on the exterior is also significant, in that instead of having columns surrounding the entire building, the pillars are instead only placed on the central portion of the building. In this way, the exterior stonework reflects the importance of the central ordinance space, where the most essential work of the temple occurs.
The new Philadelphia temple is one of the most stunning and beautiful temples of the church. This new house of the Lord stands as a monument, not only to the Savior who has given us all things, but to the founding fathers and mothers, who gave so much, that we might have the freedoms we enjoy today.
 Temple Fact sheet from Mormonnewsroom.org
 Temple Fact sheet
 Mural information from Linda Christensen
 Temple Fact sheet
 New Mormon Temple opens in Philadelphia, Washington Post
 Lily Meaning and Symbolism
 The Lost Language of Symbolism, Alonzo Gaskill, page 129
Special thanks to Brian Olson who shared his plan elevation of the temple, and for his many insights about the the new temple.