Pan means “all”, and theos means “gods”. The breakdown of the name thus makes it clear that the Pantheon served as a temple for the Greek gods. Whether the Pantheon was indeed used for this purpose, we will never know.
The walls of the Pantheon were made from Roman concrete. The Pantheon is so significant because it is a mixture of two entirely different architectural styles: Ancient Roman architecture and Greek architecture.
The main structure of the building, which holds everything together, is referred to as the rotunda, which is Italian for “round”. The rotunda was the first element of the Pantheon to be built while making use of the Roman concrete system.