The only remaining structure from the second temple left standing after the Roman destruction. Since the Jews are considered to be in a state of “ritual impurity” until certain special sacrifices can be brought (notably the ashes of the red heifer), some authorities hold religious Jews are forbidden to set foot on the actual site of the temple and this is the closest they can come to praying at the temple site. Others hold, however, that Jews may ascend the Temple Mount compound and are only forbidden to enter certain areas inside it.