Identify.

Temple of Mercury, Baiae (Bay of Naples), Augustan, not a temple for Mercury but a public Roman bath, it was the largest dome in the world until the construction of the Pantheon (71 ft in diameter), good example of innovations with concrete, oculus (opening on the top allowing light to come in, throughout out the day it shines light on different parts of the interior of the dome), made out of tufa blocks and concrete, does not appear large because the vertical part of the wall is short, learning curve (when they built the Pantheon they made the vertical part of the wall higher)