In the decade of the 1960’s the remains of a large building were discovered, 65 m southeast of the Library of Hadrian in Athens. The temple-like construction with dimensions 87 m and 39 m was identified with the Pantheon built under Hadrian. Recent research in the Library of Hadrian discovered a number of architectural features that match the colossal size of the building. Column bases and drums, as well as fragments from the superstructure, mostly incorporated in second use in the Tetraconch building, allow for the reconstruction of the outer and interior orders and their association with the in situ remains. The raised panels in the ashlars of the masonry, together with the octastyle prostyle plan which was used only during Hadrian’s year...