Eight meters (26 feet) below the present-day street level of Judaism’s holiest site, in the underground area known as the Western Wall Tunnels, a magnificent structure hidden for the last 1,700 years was recently uncovered by the Israel Antiquities Authority.

While removing a layer of earth for other purposes, archaeologists were shocked to discover the remains of what appeared to be a Roman-era theater. The find confirmed contemporary accounts of a theater close to the Temple Mount. Officials were quick to hold a press conference to present the find deep below Jerusalem’s most sacred ground.

Since the start of archaeological research in Jerusalem more than 150 years ago, excavators have been eagerly seeking public buildings mentioned in historical sources. Such descriptions can be found in the writings of Josephus Flavius and other sources from the period following the destruction of the Second Temple, when Jerusalem was renamed as the Roman colony of “Aelia Capitolina.” Many theories have been presented regarding the location of these complexes, but confirmation by means of archaeological findings was lacking. What is today called Wilson’s Arch...