主题：希腊罢工影响到希腊旅游 -- 晨枫

穹顶的材料有混凝土，有砖，混凝土用浮石作骨料。大概是先用砖沿球面砌几个大发券，然后才浇筑混凝土的。这些发券的作用是，可以使混凝土分段浇筑，还能防止混凝土在凝结前下滑，并避免混凝土收缩时出现裂缝。为了减轻穹顶重量，越往上越薄，下部厚5.9米，上部1.5米。并且在穹顶内面做五圈深深的凹格，每圈28个。

Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome

The 4,535 metric tons (4,999 short tons) weight of the Roman concrete dome is concentrated on a ring of voussoirs 9.1 metres (30 ft) in diameter that form the oculus, while the downward thrust of the dome is carried by eight barrel vaults in the 6.4 metres (21 ft) thick drum wall into eight piers. The thickness of the dome varies from 6.4 metres (21 ft) at the base of the dome to 1.2 metres (3.9 ft) around the oculus. No tensile test results are available on the concrete used in the Pantheon; however, Cowan discussed tests on ancient concrete from Roman ruins in Libya, which gave a compressive strength of 2.8 ksi (20 MPa). An empirical relationship gives a tensile strength of 213 psi (1.47 MPa) for this specimen.[27] Finite element analysis of the structure by Mark and Hutchison[28] found a maximum tensile stress of only 18.5 psi (0.128 MPa) at the point where the dome joins the raised outer wall.[29] The stresses in the dome were found to be substantially reduced by the use of successively less dense aggregate stones in higher layers of the dome. Mark and Hutchison estimated that, if normal weight concrete had been used throughout, the stresses in the arch would have been some 80% higher. The interior coffering not only was decorative but also reduced the weight of the roof, as did the elimination of the apex by means of the oculus.