Gate to the Dung Gate used to pass under this arch in the Middle Ages. The road passing over the arch is about 80 feet above the rock. But the rock under the western pier is 10 feet higher than under the Noble Sanctuary, and the lowest point in the valley is about 16 feet west of the Sanctuary wall. Westward of the pier the Street of the Chain rests upon a Causeway, made up of a complication of structures difficult to describe. There is a long passage or tunnel running along under the street, which for convenience is called the "Secret Passage." North of this run two parallel rows of vaults, which are broken up by more recent work, apparently Saracenic. But when the vaults were made they interfered at one place with a very ancient chamber of drafted stones, the "Ancient Hall," which has all the appearance of being one of the oldest buildings in Jerusalem. A shaft was sunk in the floor of the chamber to a depth of 11 feet 6 inches, through rough masonry as hard as a wall, but without finding rock. With regard to the Secret Passage, an Arabic writer, Mejr ed Din, says that the Street of David is "so named from a subterranean gallery which David caused to be made from the Gate of the Chain to the Citadel called the Mihrab of David. It still exists, and parts of it are occasionally discovered. It is solidly vaulted." It would, however, be unsafe to accept the Arab writer's opinion as to the date and use of the passage.
As touching the original contours of the ground, it appears from the excavations in the Tyropœon that two valleys descend, one from the Damascus Gate, the other from near the Jaffa Gate, and that they were originally very deep, giving the lower part of the north-western hill a rounded and gibbous form. The accumulation of rubbish at Wilson's Arch is 80 feet, at Robinson's Arch it is still more, and the true bed of the valley passes under the Haram and comes out on the south side at a distance of
