In an interview with Aaron Klein’s Investigative Radio programme on New York’s WABC Radio, Eilat Mazar claims that the 2nd Jewish temple is just ‘waiting to be unearthed’. You can read the interview here.
Although I would agree that many remains of the First and Second temple period are still existing below the surface of the present-day Temple Mount, I doubt if any remains of the Temple building itself are still extant.
The reason for this is that the floor of the Dome of the Rock and its surrounding area is actually 5 feet (1.5 m) lower than the top of the foundation of the Second Temple, which, according to Josephus was 10 feet 4 inches (3.15 m) high.
There is, however, the possibility that the foundation trenches which were usually cut into the bedrock are still existing.
The bedrock falls to the east of the Dome of the Rock and I believe that remains of the steps leading up to the Temple, the Altar, and the Nicanor Gate could still be found.
The Temple was built on the top of Mount Moriah and therefore the further away from the top, the better the chances are that remains could be found.
HT: Joe Lauer