Today on a Channukah tiyul, we walked through a newly opened 400m long ancient tunnel at Armon Hanetziv (just by the Tayelet). It is part of a water system originally developed by the Hasmonean kings that once brought water to the Temple in Jerusalem! (...and water still flowed through here in the early 20th Century) The kids had a great time.
The springs that produced the water originated south of Gush Etzion at Ein Koziba and flowed through the hills in an aqueduct over 20 km long to Har Habayit! Another aqueduct was built by Herod originating just below Efrat, flowing through Bethlehem and arriving at Herod's palace at Jaffa gate/Migdal David! These engineering feats are just incredible. They calculated the precise elevations in order to keep the water flowing (20 km long, descending only 85 m in height!)
My kids are old hands at these ancient aquducts having visited the water system around Efrat many times. My son is more familiar with the ins and outs of the water to the Beit Mikdash than he is with the Center of town in modern day Jerusalem! He spent teh tour correcting the tour guide. It seemed a very appropriate tiyul for Channuka, connecting to the Temple and the Hasmonean kings and it is very cool to go "back in time" visiting places which have such historic and archeological value just 500 metres from where I work.
Unfortunately, today we seem to be experts at wasting water and abusing our scarce water sources. We have alot to learn from the ancients.
(Details of the tiyul are here and here)