A new section of the Lower Aqueduct built by the Hasmoneans to bring water to Jerusalem has been exposed near Har Homa between Bethlehem and Jerusalem. A press release from the Israel 

Antiquities Authority gives more details.

The Israel Antiquities Authority conducted an archaeological excavation there following the discovery of the aqueduct. According to Ya’akov Billig, the excavation director, “The Lower Aqueduct to Jerusalem, which the Hasmonean kings constructed more than two thousand years ago in order to provide water to Jerusalem, operated intermittently until about one hundred years ago. The aqueduct begins at the ‘En ‘Eitam spring, near Solomon’s Pools south of Bethlehem, and is approximately 21 kilometers long. Despite its length, it flows along a very gentle downward slope whereby the water level falls just one meter per kilometer of distance. At first, the water was conveyed inside an open channel and about 500 years ago, during the Ottoman period, a terra cotta pipe was installed inside the channel in order to better protect the water”.
The aqueduct’s route was built in open areas in the past, but with the expansion of Jerusalem in the modern era, it now runs through a number of neighborhoods: Umm Tuba, Sur Bahar, East Talpiot and Abu Tor. Since this is one of Jerusalem’s principal sources of water, the city’s rulers took care to preserve it for some two thousand years, until it was replaced about a century ago by a modern electrically operated system. Due to its historical and archaeological importance, the Israel Antiquities Authority is taking steps to prevent any damage to the aqueduct, and is working to expose sections of its remains, study them and make them accessible to the general public.
The Umm Tuba section of the aqueduct was documented, studied, and covered up again for the sake of future generations. Other sections of the long aqueduct have been conserved for the public in the Armon Ha-Natziv tunnels, on the Sherover promenade, around the Sultan’s Pool and additional projects are planned whose themes include the Lower Aqueduct.

The story is reported by the Jerusalem Post, Arutz-7, and The Times of Israel. A more complete report of an earlier excavation of this aqueduct is available in Excavations and Surveys in Israel 2011.

The Pictorial Library of Bible Lands includes a 50-slide presentation on the entire ancient aqueduct system.

UPDATE: Joseph Lauer sends along a link to three high-res photos.