This is a typical Roman style temple. Generally, the Greeks built temples closer to the ground with space inside the temple for worshipers. The Roman temple was fashioned with space for worshipers outside in a courtyard. The temple was high off the ground and only the priests were allowed inside. In the rear of the Temple of Apollo was a room that only the high priest could enter. It was like the "Holy of Holies" in the temple in Jerusalem. (I'm very suspicious that many ancient temples were patterned after the layout of the Jerusalem temple. King Solomon was very influential in his day.)
The bronze statue of the pagan god Apollo is a reproduction of the original, which is housed in the National Archeological Museum in Naples. On the opposite side (out of view) is what remains of a bronze statue of Diana, Apollo's sister. Some believe that Mercury was also worshipped here.