The AP is reporting in an article carried by Yahoo! that archaeologists in Jerusalem have uncovered 100 meters of a tunnel that was built during the Second Temple period.  Although originally designed as a drainage channel, the tunnel was used by many Jews to escape from Jerusalem during the Roman seige in 70 CE.  The archaeologists seem to draw this conclusion by connecting the tunnel with one mentioned by Josephus in The Wars of the Jews.  The tunnel seems to run from the Temple Mount to the Kidron Valley.

Hat tip: Charles Halton at Awilum.