the best preseved of all roman temples is the pantheon in rome lt is famosus for its massive entrance portico and colossal circular dome which was the biggest such structure of its time and is still the largest unreinforced concrete dome in the world. the pantheon was built on the site of a temple rhat had been destroyed in a fire. Historians used to attribute the pantheon to the emperor hadrian (reigned 117-138 ce) and his architects. recent archaeological work shows. however that some of the bricks used in its construcion are frome an earlier period so the work may have begun under the emperor trajan (reigned 98-117 CE) and been finished under Hadrian.
Most romantemples were rectangular and surrounded by colummns in a similar way togreek buildings such as the Parthenon (see pp.20-23). The pantheon is however different. lts portico leads to a rectangular vestibule and beyond