From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

Holon 1. A city of Judah in the Hebron hills, given to the Levites (  Joshua 15:51;   Joshua 21:15 ). In the parallel passage   1 Chronicles 6:58 it is called Hilen . The ruin Beil Aûla , in the lower hills west of Hebron, would be a suitable site. 2. A city of Moab near Heshbon (  Jeremiah 48:21 ). Its site has not been recovered.

Smith's Bible Dictionary [2]

Ho'lon. (Sandy).

1. A town in the mountains of Judah. One of the first group, of which Debir was, apparently, the most considerable.  Joshua 15:51;  Joshua 21:15. See Hilen .

2. A city of Moab.  Jeremiah 48:21 only. No identification of it has yet taken place.

Fausset's Bible Dictionary [3]

1. A town in the mountains of Judah; allotted to the priests ( Joshua 15:51;  Joshua 21:15); HILEN in  1 Chronicles 6:58.

2. A city of Moab, in "the plain country" or level downs ( Mishor ) E. of Jordan.

Holman Bible Dictionary [4]

 Joshua 15:51 Joshua 21:15 1 Chronicles 6:58 Jeremiah 48:21

Morrish Bible Dictionary [5]

1. City of Moab in the low country, east of the Jordan.  Jeremiah 48:21 . Not identified.

2. City in Judah. See HILEN.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

(Heb. Cholon', חֹלוֹן or חֹלֹן , Sandy), the name of one or two places.

1. (Sept. ᾿Ηλών , ᾿Ωλών , etc.; Vulg. Holon, Olon.) A city in the mountains of Judah ( Joshua 15:51, where it is mentioned between Goshen and Giloh); assigned to the Levites ( Joshua 21:15, where it is mentioned between Eshtemoa and Debir); in the parallel passage ( 1 Chronicles 6:58) it is written HILEN (Heb. Chiet', חַילֵן ; Sept. Νηλών , but transposes with Jether; Vulg. Helon). De Saulcy is inclined to identify it with the village Nuhhalin, on the hills (Dead Sea, 1, 453, 454) west of Bethlehem, or, according to Dr. Robinson (new ed. of Researches, 3, 284), at the bottom of wady el-Musurr, on its southern side; but this is not in the same group of towns with the others, which all lie in the south-west part of the mountain district (Keil, Comment. ad loc.). The position seems rather to correspond to that of Beit Amreh, a large ruined village on a hill near wady el-Khulil, northwest of Juttah, on the road to Hebron (Robinson, Researches, 2, 629 and note).

2. (Sept. Χελών ,Vulg. Helon.) A city of Moab ( Jeremiah 48:21). It was one of the towns of the Mishor, The level downs (A.V. "plain country") east of Jordan, and is named with Jahazah, Dibon, and other known places; but no identification of it has yet taken place, nor does it appear in the parallel lists of Numbers 32 and Joshua 13. Smith. Perhaps it is the same as HORONAIM (See Horonaim) (q.v.)

International Standard Bible Encyclopedia [7]

hō´lon ( חלן , ḥōlōn or חלון , ḥōwlōn ):

(1) One of the towns in the hill country of Judah ( Joshua 15:51 ) assigned to the Levites  Joshua 21:15 ). In  1 Chronicles 6:58 (Hebrew 43), it is Hilen (which see). The site may be the important ruins of Beit ‛Alam (see PEF , III, 313, 321, Sh Xxi ).

(2) Probably once an important town in the "plain," i.e. plateau, of Moab ( Jeremiah 48:21 ); the site is unknown.