Note that the original Jerusalem was protected on three sides by deep valleys. From east to west these were: the Kidron, the Central Valley and the Hinnom. The Kidron, 150 feet below the top of the city, protected it on the east. Another valley ("Valley" in the photo on the right) was on the western side of the original city. (Josephus calls it the Tyropoeon, Cheesemakers. It has been largely filled in by garbage and sewage, but in antiquity it was deep.) A third valley (pictured above) comes in from farther west and meets the the first two. This is the Hinnom, Gai Benai Hinnom in Hebrew, which came to be called Gehenna (associated with hell).  The meeting of these valleys marks the southern limit of the original city. Thus the original Jerusalem, about 300 yards long by 80 wide, had excellent natural defenses on all sides except the north, where a saddle (12 feet deep) linked it to the "plateau of Benjamin" (see below).

On its north side begins a plateau (10 miles south-to-north by 4 miles east-to-west). (Since most of it belonged to the tribe of Benjamin, we can call it the Benjamin plateau.) The southernmost good link road between the international trade routes here met the only north-south route in the central highlands.

The link road between the international routes used an unbroken ridge (rare in these parts), ascending from the west through Beth Horon toward Gibeon on the plateau, then descending to Jericho and crossing the Jordan to Heshbon on the King's Highway.

The photograph (left)  shows the western part of the ridge road,  not included in the map above.

Armies coming from the west to attack Jerusalem tended to take this unbroken ridge road, reaching the plateau and turning south: for example, the Seleucids on their second attempt to squash the Maccabean revolt, the Romans under Cestius Gallus, the Crusaders, and the British in 1917.