Hydraulic engineers 2,000 years ago brought water from a collection of springs 15 miles south of Jerusalem to the Temple Mount. The water flowed through a series of pools, aqueducts and tunnels on its way to its destination in the cisterns and pools of Jerusalem. The route followed was often serpentine in order to preserve at every point the small altitude gradient that allowed this gravity-driven system to work. The features of the different sections of the water system are described below and keyed to the numbers on the map.

Arrub Aqueduct (1–17): 1. Barrel-vault over spring; 2. segment hewn into rock; 3. crossing of brook (two building phases evident); 4. Arrub pool; 5, 6. crossing of brook on dam 4 to 5 meters thick; 7. crossing of brook on dam 23 meters long; 8, 9. tunnels through ridges; 10. square guard fort; 11. channel hewn 2.5 meters into rock for 25 meters; 12. crossing of brook on bridge; 13. cutting through ridge; 14. 156-meter-long tunnel through ridge; 15. crossing cliff-face in channel 2.5 meters deep; 16. crossing Wadi Artas on dam; 17. hewn channel and short tunnel crossing cliff-face.

Low Level Aqueduct (18–22): 18. segment of old aqueduct hewn in rock; 19. hewn channel, from old aqueduct; 20. channel and short tunnel, from old aqueduct; 21. cisterns and agricultural installations along aqueduct; 22. opening of tunnel on Jebel Mukabbir.

Wadi Biyar Aqueduct (23, 24): 23. end of Wadi Biyar tunnel, ancient pool and modern dam; 24. tunnel.

Upper Level Aqueduct (25–29): 25. hewn and constructed segments on rocky slope; 26. pipe built of huge stone segments; 27, 28. hewn sections; 29. constructed section.

Herodium Aqueduct (30–33): 30. hewn sections; 31. hewn and constructed sections; 32. crossing of brook; 33. hewn and plastered sections in soft limestone.