Question
Where was the Valley of Jehoshaphat?
No one knows for certain: the valley of Jehoshaphat is named only by the prophet Joel, and most commentators take it as a symbolic name, “the valley where the Lord judges”, rather than a place on the ground. Since at least the fourth century AD tradition has put it in the Kidron valley, the deep valley between the Temple Mount and the Mount of Olives on the east side of Jerusalem, and the map follows that tradition: its point stands in the Kidron, about 0.7 km north-east of the map's point for Jerusalem and 0.6 km from the Mount of Olives in a straight line. History Globe has an article on the valley; this answer keeps to where it was sought.
Joel uses the name twice: “I will also gather all nations, and will bring them down into the valley of Jehoshaphat, and will plead with them there for my people”, and “Let the heathen be wakened, and come up to the valley of Jehoshaphat: for there will I sit to judge all the heathen round about.” Two verses later the same place is “the valley of decision”. The name means “the Lord judges”, which suits the oracle whatever valley Joel meant. Some link it with the valley of Berachah, where King Jehoshaphat and his people blessed the Lord after the enemy armies destroyed one another, south of Jerusalem near Tekoa; others with the great valley Zechariah sees opening when the Mount of Olives is split “toward the east and toward the west”.
Eusebius' Onomasticon and the pilgrim from Bordeaux, in AD 333, already place the valley of Jehoshaphat at the Kidron. Jews, Christians and Muslims came to expect the Last Judgment there, which is why the slopes hold the great Jewish cemetery of the Mount of Olives and Muslim graves under the eastern wall of the Old City. At the valley floor stand rock-cut tombs of the Second Temple period, named by later tradition the Tomb of Absalom, the Tomb of Zechariah and the Tomb of Jehoshaphat. The Kidron is the valley the map shows; whether Joel had it in mind cannot be known.
Scripture: Joel 3:2; Joel 3:12; Joel 3:14; 2 Chr 20:26; Zech 14:4
Sources
- Eusebius, Onomasticon, s.v. Koilas Iosaphat (C. U. Wolf's translation, no. 620)
- Itinerarium Burdigalense (the Bordeaux Pilgrim, AD 333)
- J. L. Crenshaw, Joel (Anchor Bible, 1995)
- H. W. Wolff, Joel and Amos (Hermeneia, 1977)
- J. Murphy-O'Connor, The Holy Land: An Oxford Archaeological Guide (5th ed., 2008)
- History Globe article “Valley of Jehoshaphat”
- Straight-line distances between the places' points (the Valley of Jehoshaphat, Jerusalem, the Mount of Olives): OpenBible.info Bible Geocoding Data (CC BY 4.0)
Checked against its sources; not yet read by a historian.