Cities of Refuge. Moses, at the command of God, set apart three cities on
the E. of Jordan, and Joshua added three others on the W., whither any person might flee for refuge who had killed a human creature inadvertently. The three on the E. of Jordan were Bezer, Ramoth, and Golan; the three on the W. were Hebron, Shechem, and Kedesh.
(Deut. iv: 43; Josh. xx : 1-8.)
from Everybody's Cyclopedia, 1912.
Refuge, Cities of, in Jewish law and history, six Levitical cities divinely appointed as places of refuge to one who had committed manslaughter, and was pursued by the "Revenger" or "Avenger" of Blood. If the case was proved to be one of murder, the perpetrator might be taken from the City of Refuge and put to death; if it was only manslaughter, the refugee had to remain in the city to which he had fled until released by the death of the high priest.
Entry from Everybody's Cyclopedia,
(I don't know why there are two entries under C and R respectively, or why they differ slightly.)