The Pantheon is an iconic piece of Ancient Roman architecture, and certainly one of the most-emulated buildings in history. Pantheon clones can be seen around the world, and buildings that borrow at least some features from Pantheon buildings are even more common. The Elks National Memorial is one of these buildings. Its dome is an almost exact replica of the Pantheon's: low, with a central oculus, coffers surrounding the oculus, and a rotunda with walls that match the diameter of the dome. However, it is otherwise a more unique interpretation. While the Pantheon is iconic not just for its dome, but also its portico front, the Elks National Memorial does not have a front portico. Instead, it has an encircling colonnade, which was inspired by the US Capitol in Washington DC. The architect of Elks National Memorial, Egerton Swartwout, claimed this building to be Roman, but also decidedly American. This could be seen in the building's overall structure: the dome of the Pantheon, but the encircling colonnade of the US Capitol.
It's important to distinguish between two prominent versions of the US Capitol: the 1818 version, and the 1863 version. The 1818 version had a traditional dome and portico design inspired by the Pantheon. The 1863 version, however, brought a much more innate dome that was also much taller. This is the design that stands today, with the encircling rotunda. The chronology of these designs, as they fit in with Elks National Memorial, shows the fascinating hierarchy of Pantheon-inspired buildings. While the 1818 US Capitol was Pantheon-inspired, the 1863 design ventured away from its blatant inspiration. Then, in 1926, the Elks National Memorial showed a combination of the Pantheon and the 1863 US Capitol, which itself had an intimate connection to the Pantheon in 1818. The Pantheon has become so deeply intertwined in architecture, its DNA can be found even in buildings that have evolved into more unique designs.
Sometimes, this generational hierarchy can obfuscate the true inspiration for Pantheon-esque buildings. Thomas Jefferson's 1826 design for The Rotunda at University of Virginia was directly inspired by the Pantheon, but the inspiration for John Russell Pope's Jefferson Memorial, completed in 1943, is not as obvious. Yes, it once again largely mimics the dome and portico design of the Pantheon, but it's also built as a memorial to Jefferson, who designed his own Pantheon-inspired buildings. Is the Jefferson Memorial an ode to the architecture of the Pantheon, or an ode to Jefferson's Pantheon-esque architecture? Such is the confounding nature of Pantheon-inspired buildings considering their long and prolific history. The Jefferson Memorial is also interesting in that it was built after the Elks National Memorial, and actually shares its design of the encircling colonnade. Thus, there is even the potential that it was inspired by the Elks National Memorial to some extent. This combination of Pantheon and potentially Elks inspiration can also be seen in the District of Columbia War Memorial, built in 1931. Once again, it shares the Pantheon's dome, but it also has the encircling colonnade of the Elks National Memorial, and even more crucially, it serves the same functional purpose as a World War I memorial.
While the Elks National Memorial is the only building in Chicago that mimics the rotunda design of the Pantheon, there is another building in the city that shares architectural influence with the Pantheon: The Museum of Science and Industry. Built for the Columbian Exposition, it largely has Greek influence in its architectural flourishes, but its overall low dome and portico design is clearly another Pantheon-inspired design.