“Section of Tholus on Dome of U.S. Capitol,” by Thomas U. Walter, 1859
In referring to the lantern on top of the dome that carried the Statue of Freedom, architect Thomas U. Walter preferred using the Greek term for any round structure--Tholus.
This drawing shows the divisions of the statue's five sections as well as its internal supports. It also shows the top portions of the dome's supporting iron trusses.
Architect of the Capitol